PASCOS 2026

22 Jun 2026, 07:00 → 26 Jun 2026, 20:25 Europe/London

Richard Roberts Auditorium

PASCOS 2026, the 31st International Symposium on Particles, Strings, and Cosmology, will be held in Sheffield from June 22 to 26, 2026. The conference aims to highlight recent advances in particle physics, astroparticle physics, string theory, and cosmology, with a strong focus on the interplay between these fields.

The conference includes invited plenary talks and parallel sessions. We warmly encourage participation from early-career researchers, and submission of abstracts for contributed talks and posters.

Topics will include:
LHC physics, dark matter and dark energy, string theory, neutrino physics, precision measurements, non-accelerator probes of new physics, inflation, gravitational waves, cosmic tensions, and modified gravity.

Invited speakers:

• Tessa Baker
• Martin Bauer
• Francesco Benini
• Florian Beutler
• Robert Brandenberger
• Philippe Brax
• Miranda Cheng
• Djuna Croon
• Tamara Davis
• Francesca Di Lodovico
• Diksha Jain
• Albrecht Klemm
• Julien Lesgourgues
• David Mulryne
• Sara Pasquetti
• Hiranya Peiris
• Vivian Poulin
• Diego Redigolo
• Adam Riess
• Andreas Ringwald
• Sakura Schäfer-Nameki
• Stefan Soldner-Rembold
• Joel Swallow
• Sally Shaw
• Luigi Tizzano
• Alessandro Tomasiello
• Sebastian Trojanowski
• Iacopo Vivarelli
• Fergus Wilson

 

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Monday 22 June

Registration

Welcome

Conveners: Alexander Fletcher, Carsten van de Bruck (University of Sheffield), Eleonora Di Valentino (University of Sheffield)

Particles

1 Axion Physics and Detection

We review the motivation for the axion as a solution of the strong
CP puzzle. We discuss benchmark axion models and present their predictions concerning
(i) axion couplings to the Standard Model and (ii) axion dark matter abundance.
We give an overview on the discovery potential of current and planned
axion experiments, reaching from direct production and detection
of axions in the laboratory, over searches for solar axions,
to axion dark matter direct detection.

Speaker: Andreas Ringwald

2 X-ray Smoking Guns from Galactic Center Compact Stars: A New Probe of Inelastic Dark Matter

An inelastic structure is a classic feature of many dark matter (DM) models arising from symmetry breaking, and investigating transitions between states with small mass splittings allows for the identification of unique, detectable signatures. While such inelasticity is a characteristic hallmark of well-motivated scenarios like Higgsino DM, it leads to particularly striking phenomenology in light hidden sectors. In this talk, we present a novel probe of this paradigm utilizing the extreme environment of the Galactic center. We investigate the capture and upscattering of DM within compact stars as they traverse the central DM density spike. Accelerated DM becomes trapped and upscatters into excited states that, following geodesics, can escape the stellar volume to decay semi-visibly in the vacuum outside. We show that the resulting X-ray signals could provide a possible origin for observed Sgr A* flares, while carrying distinct "smoking-gun" features. Using an inelastic dipole portal as a benchmark model, we demonstrate that the sensitivity of this astrophysical channel is highly competitive with that of traditional accelerator based searches, offering a powerful new frontier for identifying dark matter.

Speaker: Sebastian Trojanowski

Coffee Break

Strings

3 Challenging the Standard Paradigm of Early Universe Cosmology

Cosmological inflation has become the standard paradigm of
early universe cosmology. I will argue that this scenario, at least
when described at the level of an effective field theory, suffers
from serious conceptual problems. In light of these problems, I will
discuss a new and more consistent approach to early universe scenario
based on a proposed non-perturbative definition of
superstring theory (the BFSS matrix model). I will indicate how
a continuous, infinite and spatially flat space can emerge from
this starting point, and discuss specific predictions for cosmological
observables.

Speaker: ROBERT Brandenberger (McGill University)

4 Planar abelian mirror duals of 3d Chern-Simons matter theories

We show that a broad class of 3d N=2 chiral Chern-Simons matter theories admit an abelian and planar dual description.
These chiral-planar dualities emerge by performing real "axial" mass deformations on known N=4 mirror pairs, to flow to chiral theories on the electric side. While identifying the correct dual vacuum is subtle due to the rich structure of the Coulomb branch, we develop a mirror dualization algorithm that streamlines this process and systematically provides the abelian-planar duals of chiral quivers.
Building on these SUSY results, we propose a planar abelian dual of 3d QCD with bosons and fermions.

Speaker: Sara Pasquetti (Milan-Bicocca University)

Lunch

Cosmology

5 Galaxy Evolution Meets Cosmological Inference

Next-generation cosmological surveys — LSST, Euclid, Roman — will be limited not by statistical power but by systematic uncertainties rooted in our understanding of galaxy populations. Photometric redshift calibration, intrinsic alignments, and baryonic effects on the matter power spectrum are all manifestations of the same underlying problem: cosmological inference requires an accurate model of the galaxy population and its evolution. I will present pop-cosmos, a simulation-based inference framework that learns the joint distribution of galaxy properties — redshift, stellar mass, star formation history, dust, metallicity, and black hole activity — from deep multiwavelength photometric data. The resulting generative model simultaneously delivers calibrated redshift distributions for weak lensing tomography, enables physically-motivated sample selection that mitigates intrinsic alignment contamination and unlocks multi-tracer clustering analyses, and provides improved Type Ia supernova standardisation through host galaxy property inference. It also reveals the astrophysical processes — including black-hole-driven feedback and the cessation of star formation — that shape the very populations we use as cosmological tracers. I will show applications spanning the Kilo-Degree Survey, DESI, the Zwicky Transient Facility, and COSMOS-Web, illustrating how a unified model of galaxy evolution connects to the next generation of cosmological constraints.

Speaker: Hiranya Peiris

6 Physical, Viable and Predictive Models of Dark Energy

Recent combinations of BAO, supernovae and CMB data prefer cosmologies with an evolving dark energy equation of state, w(z), which crosses the phantom divide (w=-1). But parameterisations of w(z) are not, in themselves, complete physical models of dark energy.

In this talk we’ll ask: what kind of underlying modified gravity or dark energy models give rise to phantom-crossing behaviour? We’ll see that crossing the phantom divide can have strong consequences for other observables, particularly for ISW-galaxy cross-correlations and voids.

I’ll present a system to triage the large gravity model space down to a set of viable, predictive theories which can be verified or falsified with Stage IV galaxy surveys.

Speaker: Tessa Baker

7 Dark energy and screening

Recent surveys suggest that dark energy could be dynamical and cross the phantom divide. This can be easily reproduced in scalar-tensor theories where
matter couples to dark energy. This potentially leads to serious gravitational problems in the solar system which can be evaded thanks to screening. I will argue that
multi-field models could both reconcile phantom crossing and screening.

Speaker: philippe brax (CEA)

Coffee Break

Particles

8 Direct Detection of Dark Matter: Status and Prospects

Despite overwhelming astrophysical evidence that approximately 84% of the matter in the Universe is dark and fundamentally distinct from ordinary matter, terrestrial experiments searching for direct interactions of dark matter particles have yet to observe a convincing signal. Over the past two decades, dramatic gains in experimental sensitivity have been driven by the development of liquid noble-element detectors, and now specialised low-threshold searches and novel detector technologies are extending the search toward lighter dark matter candidates. In this talk, I will review the current status of direct detection experiments, highlight recent results, and discuss future prospects on the path toward discovery.

Speaker: Sally Shaw (University of Edinburgh)

9 Direct Searches for New Physics at the LHC: From Run 2 to the HL-LHC Era

This talk will review the status of direct searches for physics beyond the Standard Model at the LHC, from the mature Run 2 programme to the emerging Run 3 landscape and the prospects of the HL-LHC era. After a broad overview of established search programmes—including supersymmetry, dark matter, heavy resonances —the discussion will focus on what is genuinely new in Run 3: not simply increased centre-of-mass energy and integrated luminosity, but also improved detector performance, upgraded trigger capabilities, and new strategies. The talk will conclude with a forward-looking perspective on Run 4 and the HL-LHC, where both the opportunities and the challenges for direct BSM searches will become qualitatively different, requiring increasingly creative approaches to probe elusive new physics.

Speaker: Iacopo Vivarelli (Universita e INFN, Bologna (IT))

Welcome Drink + Poster Session

Tuesday 23 June

Strings

10 TBA

Speaker: Francesco Benini

11 Learning Quantum Field Theory: A Generative AI Approach

Simulating quantum field theories on the lattice is the most trustworthy first-principles way to study a theory. Computationally, this can be challenging when the lattice becomes large or when the theory approaches a phase transition. In this talk, I will first give a review of recent efforts to apply generative AI to this simulation task. Next, we turn to the question: what have these neural samplers actually learned about the underlying physical theory? Surprisingly, samplers trained with only the bare coupling constants as input can be shown to encode crucial physical information when studied in the right representation. By looking at the trained neural network parameters alone, one can discover phase transitions and even measure critical exponents, suggesting the fascinating interpretation of generative AI models as a new type of physical observable.

Speaker: Miranda Cheng

12 TBA

Speaker: Sakura Schafer-Nameki (University of Oxford)

Coffee Break

Cosmology

13 Large-scale structure, neutrino mass and Newtonian Motion gauge

I will briefly review the currently confusing situation regarding cosmological bounds on the neutrino mass. In the future, there is a hope to clarify the situation by detecting the actual neutrino free-streaming effect in large-scale structures. In this regard, I will present a new method allowing to easily incorporate the scale-dependance of the growth factor induced by massive neutrinos (or potentially by non-standard dark matter) in analytical predictions for the matter power spectrum, without recurring to more complicated equations, but simply by playing with specific gauge transformations.

Speaker: Julien Lesgourgues (TTK, RWTH Aachen University)

14 Mapping Cosmic Expansion with DESI: Precision BAO and the Road Ahead

Spectroscopic surveys map the three‑dimensional large‑scale structure of the Universe, providing precise tests of cosmic expansion and the growth of structure. The Dark Energy Spectroscopic Instrument (DESI) is a Stage‑IV experiment on the 4‑m Mayall telescope, using 5000 robotically positioned fibres to obtain spectra for more than 40 million galaxies and quasars over ~14,000 deg². I will briefly outline DESI’s design and survey strategy, including its target classes (BGS, LRGs, ELGs, QSOs, and the Lyα forest), and the analysis methods that underpin robust distance measurements.
I will then summarise DESI’s first cosmology results, highlighting per cent-level baryon acoustic oscillation (BAO) constraints that deliver the most precise expansion history to date across a broad redshift range. I will discuss internal consistency tests, comparisons with previous surveys, and the cosmological interpretation of these measurements within ΛCDM and simple extensions. In particular, I will examine the current hint (still at modest significance) for departures from a constant dark‑energy equation of state.
Finally, I will preview what the expanding DESI dataset will enable: tighter BAO and redshift‑space distortion measurements, improved full‑shape analyses, and sharpened constraints on curvature, gravity, and the sum of neutrino masses.

Speaker: Florian Beutler

Lunch

Cosmology: Inflation

Conveners: Konstantinos Dimopoulos, Dr Laura Iacconi (Queen Mary University of London)

15 How Sensitive is Cosmic Inflation to Quantum Corrections?

In this talk, I will present a non-perturbative framework that allows to track the dynamics of slow-roll inflation while consistently incorporating quantum corrections, based on an alternative functional renormalisation group (RG) approach. I will guide you through the derivation of a set of coupled Friedmann-RG flow equations governing the joint evolution of spacetime, the inflaton field, and its effective potential. Applying this formalism to α-attractor E-models, I will show that the RG flow induces a dynamical destabilisation of the inflationary trajectory, leading to a premature termination of slow roll. Remarkably, the resulting predictions bring α-attractors into full agreement with the latest ACT data without introducing new physics beyond a consistent quantum-corrected treatment of the inflaton dynamics.

Speaker: Lucien Heurtier (King's College London)

16 A universal scaling for induced gravitational waves during inflation

We consider the gravitational wave (GW) background induced by arbitrary source fields that are amplified during inflation. We first conduct a very general analysis where the associated tensor spectral index $n_T$ is shown to be given, under minimal assumptions, by a simple and ready-to-use formula. Remarkably, we demonstrate that during slow-roll inflation $n_T$ becomes completely independent of the original spectrum of the source, exhibiting a universal near scale invariance. We then refine our study to the case of GWs induced by abelian gauge fields, covering the case of axion inflation. We analytically derive the amplitude of GWs and argue that they can overtake the standard inflationary GW background. We use this to constrain the values of gauge field couplings allowed by observations. This presentation is based on https://arxiv.org/abs/2510.00869 and https://arxiv.org/abs/2512.14670.

Speaker: Martin Teuscher (LPSC Grenoble, France)

17 Post-Inflationary Higgs Dynamics from Spacetime Curvature

The Standard Model Higgs field, when non-minimally coupled to gravity, can display rich dynamics after inflation. In cosmological setups that include a short kination stage, the fast variation of spacetime curvature can temporarily destabilize the electroweak vacuum through curvature-induced tachyonic effects. This process can trigger a gravitationally sourced phase transition, leading to the rapid growth of Higgs fluctuations, the development of transient inhomogeneous configurations, and an efficient conversion of vacuum energy into radiation. Within the Standard Model, this provides a minimal and self-consistent reheating mechanism.

I will outline the theoretical framework underlying this dynamics and discuss its cosmological implications. The interplay between curvature, vacuum stability, and non-perturbative evolution yields a predictive scenario that connects electroweak-scale physics with potentially observable stochastic gravitational-wave backgrounds.

Speaker: Dr JAVIER RUBIO (Universidad Complutense de Madrid)

18 Discovering New Particles with Cosmic Microwave Background

Cosmological collider signals of primordial non-Gaussianity arise at tree level when a particle has Hubble mass during inflation. We critically review the formalism finding that a large class of inflationary theories, based on Planck-scale physics, predict a scalar bi-spectrum around the gravitational floor level. This mild signal arises for example in R2 gravity, in the regime where its gravitational scalar has Hubble-scale mass. Signals much above the gravitational floor arise in theories where scalars undergo multiple turns during inflation, thanks to sub-Planckian physics.

Speaker: Anish Ghoshal (University of Warsaw, Poland)

19 Primordial Black Hole Formation from Inflationary Higgs Instability

Metastability of the Standard Model Higgs during inflation raises the possibility that stochastic fluctuations push the field beyond the instability barrier and into a region of negative energy vacuum. Whether such excursions are fatal to our Universe depends on their fully nonlinear gravitational evolution. We revisit this problem using numerical simulations of a spherically symmetric gravity-scalar-fluid system. We consider an intially radiation dominated Friedmann–Lemaître–Robertson–Walker background with superhorizon fluctuations in the field, which are generated during inflation. We find that once an unstable patch enters classical collapse, it first forms a primordial black hole hiding the crunching true vacuum core within. The late time evolution is controlled by the ratio of the barrier size to its self-gravity $R_w/\ell_\sigma$. For subcritical configurations, the remaining true vacuum region is gradually swallowed by the original black hole. For supercritical configurations, the barrier briefly drives the spacetime into a wormhole-like phase with a second trapped surface and a bifurcating horizon, allowing a transient baby-universe interpretation. In all cases we study, the entire region with field values beyond the potential barrier eventually becomes hidden behind horizons, and the late time exterior is that of an ordinary primordial black hole embedded in an FLRW universe. Our results therefore suggest that field excursions beyond an instability scale are not necessarily catastrophic for the compatibility of inflation with our observed Universe. More broadly, this mechanism is not unique to the Higgs, but is expected to apply quite generally to spectator scalar fields with metastable potentials containing a negative true vacuum.

Speaker: Ethan Milligan (QMUL)

20 Coffee Break

21 Observational prospects of axion inflation

Axions are well-motivated pseudoscalar fields that arise in many extensions of the Standard Model and can drive inflation. In scenarios where an axion couples to a gauge sector during inflation, the rolling field can lead to exponential amplification of gauge-field fluctuations, with important implications for particle production, reheating dynamics, primordial gravitational wave signatures, and primordial magnetic fields.
In this talk, I will review recent progress in axion inflation with Abelian and non-Abelian gauge fields, emphasizing the resulting signatures in the primordial gravitational wave background and their correlation with primordial magnetic fields. I will further discuss how the emergence of a primordial plasma via the Schwinger effect modifies early universe dynamics, impacting reheating, the gravitational wave signal, and primordial magnetic field predictions.

Speaker: Oksana Iarygina (Nordita)

22 Primordial Power Spectrum from a deformed Bouncing background

We present the formalism of Deformed Commutation Relations, consisting in a modification of the standard Heisenberg commutator (or of the Poisson brackets in the semiclassical limit) inspired by the Generalised Uncertainty Principle representation, and its implementation to the cosmological Friedmann-Lemaitre-Robertson-Walker isotropic model. One specific form had previously been shown to yield the same exact dynamics of effective Loop Quantum Cosmology, removing the cosmological singularities and replacing them with a Bounce. Here we use this modified background to compute the evolution of perturbations during the Inflationary expansion. We obtain a modified time-dependent mass term for the Mukhanov-Sasaki equation and compare the resulting Power Spectrum with those obtained in Loop Quantum Cosmology, such as with the Hybrid or the Dressed Metric approaches.

Speaker: Gabriele Barca (University of the Basque Country)

23 Optimized numerical evolution of perturbations across sharp background trajectory turns in multifield inflation

Features in the primordial power spectrum require numerical methods that are both accurate and scalable across the wide class of multifield inflationary models that produce them. Sharp turns in the background trajectories, induced by either potential or geometric effects, render these computations particularly challenging. In this work, we introduce an efficient method for evolving primordial scalar fluctuations, requiring timesteps comparable to those used for the background evolution. We demonstrate that the method accurately tracks perturbations through rapidly turning trajectories in arbitrary field-space geometries, enabling systematic exploration of spectral features across diverse multifield scenarios. Our approach scales robustly to large numbers of degrees of freedom, providing a reliable computational framework for probing regimes that significantly depart from slow-roll dynamics.

Speaker: Guillermo Fernando Quispe Peña (Simon Fraser University)

24 Large Primordial Fluctuations: Stochastic vs. Classical $\delta N$ approaches

The classical evolution of fields during a period of accelerated expansion in the very early universe ("inflation") can establish an idealised homogeneous and isotropic cosmology. However, quantum fluctuations inevitably generate inhomogeneities and anisotropies on all observable scales and beyond. The $\delta N$ formalism provides a powerful framework to describe the nonlinear curvature perturbation in terms of fluctuations in the duration of inflation, $N$. In its standard implementation, $\delta N$ is calculated using the classical trajectory to find the number of e-folds of inflation from a given field value to the end of inflation. In contrast, the stochastic $\delta N$ formalism incorporates quantum fluctuations as stochastic noise along the trajectory, enabling a non-perturbative treatment of inflationary dynamics that can be crucial for rare, large fluctuations. In this work, we compare the classical and stochastic approaches to study the statistics of large curvature perturbations when coarse-grained at a given length scale. This is particularly relevant for calculations of primordial black hole formation. Using the numerical code PyFPT, we compute the distribution of curvature perturbations from slow-roll inflation driven by a quadratic potential, and perform a detailed comparison with the classical $\delta N$ formalism, identifying regimes where quantum diffusion significantly impacts the probability distribution of large fluctuations.

Speaker: Parth Bhargava (ICG, Portsmouth)

Cosmology: Joint MG&DE

Conveners: Alessandra Silvestri, Laura Herold, Matteo Martinelli (INAF - OAR), Supriya Pan

25 Theoretical implications of DESI BAO: the case for Nonminimal Coupling

The recent baryon acoustic oscillation (BAO) measurements from the DESI collaboration have revealed a first hint towards a deviation from a cosmological constant, signaling a preference for dynamical dark energy. In this talk, we explore the deep theoretical implications of these observations for dark energy and gravitational physics. Utilizing a model-agnostic, non-parametric reconstruction approach, we constrain the behaviour of the dark energy equation of state. Our analysis demonstrates that the combined DESI, CMB, and Type Ia Supernovae datasets favor a crossing of the phantom divide, a behavior that structurally rules out standard canonical scalar field models like quintessence due to ghost instabilities.
To interpret this result, we survey the wider scalar-tensor landscape via the Effective Field Theory of Dark Energy, within the Horndeski class of gravity theories. We identify the non-minimal coupling of gravity as the unique operator capable of stabilizing this phantom crossing, establishing the DESI results as a potential observational hint of modified gravity.

Speaker: Matteo Martinelli (INAF - OAR)

26 A Lapse in the Cosmological Constant Problem

We present a new mechanism for addressing the cosmological constant problem based on global constraints arising from a lapse function in a higher-dimensional gravitational theory. Inspired by Horava-Lifshitz gravity, we consider a 5d spacetime with anisotropic scaling along a compact extra dimension, while preserving Lorentz invariance in four dimensions. In the deep infrared limit, variation with respect to the lapse generates a global constraint on the 4d geometry, closely analogous to that of vacuum energy sequestering. Although the resulting effective gravitational equations differ from standard sequestering, radiative contributions to the Standard Model vacuum energy are nevertheless cancelled at all orders.

Speaker: Benjamin Muntz (University of Nottingham)

27 Late time behavior in f(R,Lm) gravity through Gaussian reconstruction and dynamical stability

In this paper, we explore modified gravity in the framework of $f(R, \mathcal{L}_m)$ theory by reconstructing the function $G(\mathcal{L}_m)$, where $\mathcal{L}_m = \rho$ be the matter Lagrangian, under the assumption of a pressureless, matter-dominated Universe. Using a non-parametric Gaussian process reconstruction technique applied to Hubble data, we present two cosmological models with the form of $G(\mathcal{L}_m)$ such as (i) a power-law model, $G_1(\mathcal{L}_m) = \alpha \mathcal{L}_m^{b_1}$ with $b_1 \in [0.018, 0.025]$ and (ii) an exponential model, $G_2(\mathcal{L}_m) = \alpha \mathcal{L}_{m0} \left(1 - e^{-b_2 \sqrt{\mathcal{L}_m/\mathcal{L}_{m0}}} \right)$ with $b_2 \in [2.3, 3.0]$. We then fix the parameter values within these reconstructed ranges and analyze the corresponding dynamical systems within the matter-dominated epoch by constructing autonomous equations. Phase-space analysis reveals the presence of stable critical points in both models, suggesting viable cosmic evolution within their domains of validity. Both the models exhibit stable attractor solution at late time, reinforcing their viability in explaining the late time cosmic acceleration without explicitly invoking a cosmological constant. Our results indicate that $f(R, \mathcal{L}_m)$ gravity with data-driven matter-sector modifications can offer a compelling alternative description of cosmic dynamics during the matter-dominated era.

Speaker: Yengkhom Kalpana Devi (Bits Pilani Hyderabad Campus)

28 Reconstructing Sign-Changing Dark Energy Density: From Data to Fundamental Theory

Recent cosmological observations continue to challenge the standard $\Lambda$CDM paradigm through persistent tensions in the Hubble constant $H_0$, the clustering amplitude $S_8$, and possible hints of nontrivial late-time dark-energy dynamics. In this talk, we discuss two complementary studies showing how sign transitions in the effective vacuum sector may arise naturally from modified gravity and higher-dimensional geometry. We first present new solution branches in teleparallel $f(T)$ gravity, focusing on the exponential infrared model $f(T)=T e^{T_*/T}$, where $\beta=T_*/T_0$ controls deviations from $\Lambda$CDM. While the positive-$\beta$ branch has been widely explored, the previously overlooked negative-$\beta$ branch exhibits rich and viable cosmological behavior. It predicts an effective dark-energy density that changes sign at a data-driven transition redshift, emerging around $z_\dagger\sim1.5$, rather than being imposed by hand, while remaining consistent with CMB and local gravity constraints through an effective screening mechanism [1]. Interestingly, cosmic acceleration can begin while the effective dark-energy density is still negative, highlighting the nontrivial role of modified gravitational dynamics. Adding a cosmological constant further enlarges the viable parameter space and may allow moderated or transient late-time acceleration. We then discuss, this time within unmodified general relativity, a purely geometric realization of $\Lambda_{\rm s}$CDM using a $(1+3+n)$-dimensional Kaluza--Klein framework with compact extra dimensions of constant intrinsic curvature. For a stabilized internal manifold of radius $s_*$, the internal curvature contributes $\tilde{\chi}=-n(n-1)k_{\rm int}/(2s_*^2)$, which combines with $\tilde{\Lambda}$ to define an effective vacuum term $\tilde{\gamma}=\tilde{\Lambda}+\tilde{\chi}$, yielding a background expansion degenerate with $\Lambda$CDM. A rapid transition $s_{\rm p}\rightarrow s_0$ can shift $\tilde{\gamma}$ abruptly and change its sign. Since $G_{\rm 4D}\propto s^{-n}$, the same event induces a correlated step in gravity strength, providing a key observational discriminator[2]. Together, these results show that sign-changing dark-energy density may emerge from theoretically well-established frameworks, suggesting new insight into cosmic acceleration and current cosmological tensions.

[1]Ö.Akarsu, B.Bulduk, A.De Felice, N.Katırcı and N.M.Uzun,``Unexplored regions in teleparallel $f(T)$ gravity: Sign-changing dark energy density,'' Phys. Rev. D 112 (2025), 083532, arXiv:2410.23068

[2] Ö.Akarsu, B.Bulduk, N.Katırcı, E.Özülker and L.Perivolaropoulos,``Constructing $\Lambda_{\rm s}$CDM via compact, curved extra dimensions: Coupled transitions in the effective $\Lambda_{\rm 4D}$ and $G_{\rm 4D}$,'' in preparation.

Speaker: Prof. Nihan Katırcı (Dogus University)

29 Asymptotically Cubic Galileon Gravity: Late-Time Departures for Viable Dark Energy

In this talk, we introduce Asymptotically Cubic Galileon gravity: a luminal Horndeski theory designed to remain close to the cubic Galileon over most of cosmic history, whilst allowing late-time departures that are be broadly consistent with current observations including the recent DESI results. These departures are generated by promoting the coefficients of the Galileon terms to functions of the scalar field. We show that, once this explicit field dependence is introduced, the closed theory space is fully characterised, modulo scalar-field redefinitions, by two invariant functions. Working in a convenient field parametrisation, we identify the functional behaviour these invariants must exhibit in order to lift the theory away from the cubic Galileon’s eternally phantom regime and allow a crossing of the phantom divide. We then use the ISW effect and the modified force in cosmic voids to identify phenomenologically viable regions of the theory space, before confronting these regions with DESI, Planck, and supernova data through an MCMC analysis. For the models studied, the data-favoured regions can overlap the phenomenologically viable sector, although the void modified-force condition remains the limiting constraint.

Speaker: James Hallam (Institute of Cosmology and Gravitation - University of Portsmouth)

30 Coffee Break

31 Modified gravity & friends vs current CMB data.

In this talk we will look at the evidence of the effects induced by seemingly different extensions to the standard cosmological model in the cosmic microwave background (CMB) primary and secondary anisotropies: modified gravity (through the growth index - '$\gamma$', a modification of the growth of linear perturbations in the standard model, and the '$\mu-\Sigma$' framework, a modification of the Poisson and lensing perturbation equations), massive neutrinos and non-vanishing spatial curvature. By looking at their correlations and the differences in the impact they have on cosmological observables, such as the CMB lensing spectrum, we assess whether such additions can be told apart and identify the common root to their detection: the lensing anomaly.

Speaker: Enrico Specogna (University of Sheffield)

32 A Holographic Dark Energy Model in Light of Recent Data

The latest data release of the DESI collaboration shows an increasing preference for time-depending dark energy models compared to the $\Lambda$CDM model.
In our work, we construct a holographic dark energy model motivated by the work of Cohen, Kaplan and Nelson (CKN) which proposed to use the Hubble horizon as an IR cutoff and connect it to the UV cutoff of the theory.
We take the resulting dark energy model that is proportional to $H(z)^2$ and compare it to different data sets in both, the late-universe and early-universe. Depending on the data set used, we find a preference of up to $2.6\,\sigma$ over the $\Lambda$CDM model and discuss several extensions of this model to improve the stability and sensitivity to early-universe data.

Speaker: Patrick Adolf

33 Cosmological no-go theorem in bumblebee gravity

Bumblebee gravity is currently a popular topic, and models are ubiquitus in the literature. In this talk, I will first review the current state of the art; then, I will show that the model propagates ghosts on cosmological as well as arbitrary backgrounds, resulting in a no-go theorem in the context of this model.

Speaker: Nils A. Nilsson

34 Precision gravitational wave theory at seventh post-Newtonian order

Next generation gravitational wave observatories, such as the Einstein Telescope and LISA, will require an improvement of up to two orders of magnitude in waveform model accuracy to control theoretical systematics in precision parameter estimation. In particular, robust inference of cosmological parameters and future null tests of general relativity require highly accurate predictions within general relativity itself. This makes the completion of high order post-Newtonian (PN) dynamics for compact binary systems, up to the seventh post-Newtonian order, a key target for the next decade.

This talk presents recent high order PN computations for compact binaries using Effective Field Theory and multi-loop Feynman integral techniques.
The talk focuses on the static sector of the 6PN and 7PN gravitational potential, which contains some of the technically most demanding contributions to the conservative two-body dynamics.

We first present the 6PN static potential, highlighting the techniques that enabled the evaluation of six-loop Feynman diagrams.
Next, we introduce a novel correlation function framework for the computation of static two-body interactions. This approach demonstrates that the static PN factorization theorem stems from a $\mathbb{Z}_2$ symmetry, enabling the direct determination of odd-PN static contributions from lower order data.
Using this framework, we derive a closed all order formula encoding the structure of static PN corrections, and determine the complete 7PN static potential.
We conclude by discussing extensions to this framework.

These results provide theoretical input for more accurate measurements with future gravitational wave observatories, while offering a new perspective on the classical two-body problem.
The talk is based on arXiv:2512.19498 and arXiv:2604.14134.

Speaker: Matteo Pegorin (University of Padova & INFN Padova)

Particles: Dark Matter

Conveners: Adam Brown (University of Sheffield), Christopher McCabe (King's College London)

35 DMRadio: A lumped-element, low-mass axion search

The QCD axion is a particle that has been postulated to be a solution to the strong CP problem and also a candidate for dark matter in the universe. The DMRadio suite of experiments is a resonant, lumped-element search that probes low mass axions below 1 $\mu$eV. To achieve the necessary sensitivities, the development of DMRadio involves high-field DC magnets of various geometries, tunable resonators with high quality factors, and low-noise quantum sensors near and ultimately past the standard quantum limit. In this talk, I will present the design and commissioning status of DMRadio-50L, the first experiment of the program, and the subsequent stages of DMRadio which aim to discover GUT-scale axions.

Speaker: Andrew Yi (SLAC National Accelerator Laboratory)

36 Preparedness for Dark Matter Discovery at SuperCDMS SNOLAB

The SuperCDMS SNOLAB experiment is currently being commissioned at the Canadian underground facility SNOLAB. The experiment uses four detector towers that contain 24 detectors in total, including both interleaved Z-dependent Ionization and Phonon (iZIP) and high-voltage (HV) detectors with germanium (Ge) and silicon (Si) targets. The iZIP detectors measure both charge and phonon signals and thus enable direct rejection of electron recoil backgrounds, while the HV detectors use Neganov-Trofimov-Luke (NTL) amplification to probe lower dark matter masses. Lighter Si targets provide reach to lower masses, while Ge targets of the same volume provide better cross-section reach due to higher atomic mass and absence of the $\mathrm{^{32}Si}$ cosmogenic background. The experiment is expected to achieve a total exposure of approximately $90\,\mathrm{kg\cdot yr}$ over four years. Prior sensitivity projections indicate that SuperCDMS SNOLAB will explore new dark matter phase space, probing the dark matter-nucleon cross section down to $10^{-43}\,\mathrm{cm^2}$ for masses from 1 to 10 $\mathrm{GeV/c^2}$, approaching the sensitivity needed to detect coherent elastic neutrino-nucleus scattering ($\mathrm{CE\nu NS}$) of $\mathrm{^8B}$ solar neutrinos. This contribution will give an overview of the SuperCDMS SNOLAB experiment, discuss the current status of detector commissioning and analysis preparation, and briefly highlight $\mathrm{R\&D}$ efforts for potential detector upgrades.

Speaker: Junwen Xiong (Caltech)

37 Beyond 3→2: Towards Realistic SIMP Dark Matter

Strongly interacting dark sectors with pseudo–Nambu–Goldstone bosons provide a versatile framework for sub-GeV dark matter. While the original SIMP paradigm emphasises number-changing processes as the origin of the relic abundance, the phenomenology of pionic dark matter is considerably richer. Depending on the spectrum and couplings, the relic density can WIMP-annihilations, semi-annihilations involving vector mesons and further processes like $\pi\pi\pi\to\pi\rho$. A consistent treatment therefore requires a framework that simultaneously captures pion dynamics, vector mesons, anomalous interactions, and portal effects.
We consider QCD-like dark sectors in which the dark matter candidates are pions. The effective theory is formulated using the Hidden Local Symmetry (HLS) approach, and is applicable to complex, real, and pseudo-real fermion theories.
As a minimal benchmark, we focus on the pseudo-real symmetry-breaking pattern $SU(4)/Sp(4)$.

Speaker: Halvor Melkild (University of Oslo)

38 Cornered But Alive: GeV-scale Thermal Dark Matter From Dark Photons

GeV-scale thermal dark matter is often considered to be strongly constrained by the null results of direct, indirect, and collider searches. Nevertheless, viable scenarios can still arise in well-motivated dark sector frameworks. In this talk, we explore this possibility in a dark Abelian Higgs model with a Dirac fermion dark matter candidate interacting with the Standard Model through a dark photon mediator. We focus on the intermediate mass regime for the mediator, between 10 GeV and the mass of the Z boson, which lies beyond the reach of B factories and below the typical sensitivity of the LHC, and has been comparatively underexplored in the literature.

We perform a comprehensive analysis of the complementarity between collider probes, direct detection, and indirect detection experiments, while consistently accounting for the possibility that the our candidate constitutes only a fraction of the observed dark matter relic abundance. This dilution effect relaxes the experimental limits by suppressing direct and indirect detection signals according to the dark matter relic abundance. Despite the strong experimental pressure, we show that thermal GeV-scale dark matter is cornered but still viable. The allowed parameter space is restricted to narrow regions near the resonant regime, $m_\chi\approx m_{Z_D}/2$, where dark matter annihilation in the early universe is enhanced. In this regime, direct detection experiments provide the strongest constraints, while collider searches offer complementary sensitivity for sizeable values of the kinetic mixing. Future results from both direct detection and colliders will play a crucial role in testing these remaining windows, making GeV-scale dark photon portals an attractive target for upcoming experiments.

This talk is based on 2507.11376.

Speaker: David Alonso-González (IFT (UAM-CSIC))

39 Coffee Break

40 Heavy dark matter in rapidly evolving massive stars

Dark matter (DM) constitutes most of the matter content of the Universe, yet its particle nature remains unknown. While laboratory searches and cosmological probes have placed strong constraints on many candidate models, astrophysical environments provide a complementary avenue to test DM interactions under extreme conditions. Stars are particularly promising laboratories: as they move through their host halos, DM particles may scatter with stellar constituents, lose energy, and become gravitationally captured. Once accumulated, DM can alter stellar evolution through annihilation heating, enhanced luminosity, or—in the case of heavy non-annihilating DM—through self-gravitation and eventual collapse. Understanding capture in realistic stellar environments is therefore essential for connecting stellar observations to particle DM physics.

In this talk, I will discuss the capture of heavy DM in rapidly evolving massive stars, with emphasis on the first stellar populations and their later metal-enriched descendants. Using stellar evolution simulations from the zero-age main sequence to advanced burning stages, we show that DM capture depends sensitively on the changing internal structure and composition of the star. During the early hydrogen- and helium-dominated phases, capture is largely controlled by scattering on light nuclei. As nuclear burning proceeds, metal production generates a dense core surrounded by a lighter envelope, substantially enhancing the capture of ultra-heavy DM and requiring a multi-component treatment with several nuclear targets.

I will also highlight recent advances in the theory of heavy-DM capture in compact stars, where multiple scatterings, realistic trajectories, nuclear form factors, and in-medium thermalization effects become crucial. These developments clarify how efficiently heavy DM can be trapped and transported to stellar centers, and how rapidly it can thermalize after capture.

Our results indicate that, for viable regions of parameter space beyond current direct-detection bounds, heavy annihilating DM may reach capture–annihilation equilibrium within the short lifetime of a massive star. For non-annihilating DM, the accumulated population can become self-gravitating and potentially collapse into a black hole capable of consuming the host star from within. These findings demonstrate that accurate stellar modeling, combined with improved capture formalisms, opens a powerful new window on heavy DM through massive stars and stellar remnants.

Speaker: Giorgio Busoni (Adelaide University)

41 A Solar Probe of Dark Matter Decay in the Galaxy

Dark matter (DM) decay in the Galactic halo injects energetic $e^\pm$ that can inverse-Compton scatter (ICS) solar photons into $\gamma$ rays, producing a diffuse halo of emission around the Sun. We present the first quantitative study of this signal as a probe of decaying DM. Using 15 years of Fermi-LAT solar-halo data, we compute the heliocentric ICS signal and derive limits on the DM lifetime for masses between 10 GeV and 10 TeV. For final states with the hardest spectra, we obtain constraints reaching lifetimes of $10^{27}\,\mathrm{s}$. Solar ICS $\gamma$-rays therefore provide a novel and complementary local probe of decaying DM, systematically distinct from both Galactic diffuse $\gamma$-ray searches and direct charged-particle measurements.

Speaker: Maximilian Detering (King's College London)

42 Cosmological signals of dark matter semi-annihilation

In different classes of models, semi-annihilation of Dark Matter (DM) can set the DM relic abundance. One of the most interesting features of this scenario is the generation of a boosted DM component (BDM), as part of the energy of the initial state is converted into kinetic energy of the DM particle in the final state. In this work, we consider the process $\chi \chi \to \chi^c\,\nu$, which can occur with a sizable rate in dark matter halos at high redshift. Using a state-of-the-art model for the cosmological boost factor, we compute the redshift-dependent flux of BDM particles generated via semi-annihilations and discuss the implications for structure formation and direct detection experiments. We show that the cosmological contribution can enhance the sensitivity of current DM searches by up to two orders of magnitude, and may allow future experiments to probe scattering cross sections in the femtobarn range for DM masses ranging from $\sim 10$ to $10^3$ MeV.

Speaker: Alessia Musumeci (Technical University of Munich)

43 Filtered dark matter from strong first order phase transitions

While cooling down, the early universe is believed to have undergone symmetry breaking phase transitions. One attractive possibility for extending the Standard Model is that these phase transitions are of the first order, as they might be able to produce observable gravitational waves. We consider a dark matter freeze-out mechanism, filtering, where dark matter particles become massive in a first order phase transition. Since the mass of the dark matter increases at the phase boundary, only sufficiently energetic particles are able to enter the bubbles of the new phase, while others are reflected and will be annihilated. We focus specifically on a subset of phase transitions, deflagrations, during which the bubble walls are subsonic and slowed down as they expand. As the transition proceeds, this causes heated droplets of metastable vacuum to be formed. We have found that different amounts of dark matter are produced during the initial expansion and the final slowed down droplet stage. Taking this into account, we calculate a realistic estimate for the dark matter relic abundance produced by filtering in deflagration scenarios.

Speaker: Satumaaria Sukuvaara

44 No room for monopole dark matter

The magnetic monopole of a dark sector has been advocated as an appealing dark matter candidate, since its stability naturally follows from topological arguments. I will revisit the computation of the monopole abundance generated by a thermal phase transition, exploring the three regimes where the phase transition is second order, weakly first order, or supercooled. This will allow us to identify the parameter space regions where the monopole relic density can match the observed dark matter abundance. However, a dark sector featuring monopoles necessarily contains stable electrically-charged particles, namely massive vector bosons. I will show that the abundance of gauge bosons, under minimal assumptions, is always far larger than the monopole one. This result leads to the conclusion that dark monopoles cannot constitute a sizeable fraction of dark matter in the minimal model, contrarily to what has been previously claimed.

Speaker: Théodore Fischer (LUPM)

Particles: Neutrino Physics

Conveners: IVAN MARTINEZ SOLER (Durham University and IPPP), Pasquale Di Bari

45 Status of three-flavor neutrino oscillations and the lessons from the first JUNO results

Neutrino oscillation measurements are entering a precision era, with many parameters being measured at the percent level. However, unknowns related to 3-neutrino effects remain. Determining these unknowns is important for open questions in, e.g., cosmology; but it is also key to test the global consistency of the framework and fully establish or break the 3-neutrino paradigm.
In this talk, I will argue that fully understanding these effects require a global data combination. I will discuss results and tensions stemming from this combination, including the outcome of fully analyzing the first results from the JUNO experiment.

Speaker: Ivan Esteban

46 First Physics Results from JUNO

The Jiangmen Underground Neutrino Observatory (JUNO) is a 20-kton liquid-scintillator detector designed to determine the neutrino mass ordering and perform precision measurements of neutrino oscillation parameters using reactor antineutrinos. Following the start of physics data taking in August 2025, JUNO has recorded its first reactor antineutrino sample and reported world-leading measurements of the solar oscillation parameters sin²θ₁₂ and Δm²₂₁. These results demonstrate the excellent performance of the detector and mark the beginning of JUNO’s precision neutrino physics programme. In this talk, I will present the current status of the experiment and review JUNO’s first neutrino oscillation results.

Speaker: Xianguo Lu

47 Status and Opportunities of the Hyper-Kamiokande Experiment

The Hyper-Kamiokande (Hyper-K) experiment is the third generation of underground water Cherenkov detectors in Japan. It will serve as (1) the far detector for a long-baseline neutrino oscillation experiment for the upgraded, 1.3 MW power J-PARC muon neutrino/antineutrino beam, and (2) a detector capable of observing proton decays, atmospheric neutrinos, and neutrinos from astronomical sources. The fiducial region of the Hyper-K detector, with a mass of 186 kton, will be instrumented with 20,000 20-inch photomultiplier tubes (PMTs) and 800 multi-PMT modules, each containing 19 3-inch PMTs. Tests of detector components are underway, and operation is scheduled to begin in 2028. The status of the Hyper-Kamiokande experiment, its broad neutrino physics programme, and its sensitivities to key processes, including CP violation, proton decay, and astrophysical neutrinos, will be presented.

Speaker: George Burton

48 Towards the final analysis of the KATRIN data

The KATRIN experiment aims at direct kinematic measurement of the neutrino mass with the expected sensitivity below 300 meV (90% CL), performing a high-resolution, high-statistics spectroscopy of tritium beta-decay. To reach such sensitivity, the systematic effects, modifying the measured electron spectrum shape have to be modeled and controlled by dedicated calibration measurements.
KATRIN obtained the world-leading direct constraint on the effective mass of the electron antineutrino of 0.45 eV (90% CL) using only 16% of the data. The final dataset of KATRIN contains 1000 days of tritium spectra recorded by the end of 2025 and therefore increases the statistics by a factor of 6 compared to previous results.
In this talk after introducing the framework of the analysis, the challenges and steps towards the analysis of the full KATRIN dataset are presented.

Speaker: Karo Erhardt (KIT)

49 Search for keV Sterile Neutrinos with the KATRIN Experiment

The KATRIN experiment is designed to measure the mass of the electron anti-neutrino by studying the high energy end of the tritium β decay spectrum. In addition, KATRIN is also a well suited instrument to explore the sterile neutrino hypothesis. The existence of sterile neutrinos would cause a kink-like distortion in the spectrum.
Using the same datasets as for the active neutrino mass, KATRIN has previously presented results on the search for sterile neutrinos at the eV scale, complementing the reactor and radioactive source experiments. With an endpoint of 18.6 keV, KATRIN also offers a high potential for the search of sterile neutrinos in the keV range. With data acquired during the
2018 commissioning campaign, KATRIN reported results from a search for keV-scale neutrinos in the restricted mass range of 0.01 to 1.6 keV. No keV-sterile neutrino signal was observed and KATRIN reported exclusion limits competitive with other laboratory-based searches. The current KATRIN detector is not designed to handle the higher count rate that occurs with a wider mass range. Equipped with the TRISTAN detector KATRIN
aims to search for keV sterile neutrinos across the full tritium beta decay spectrum. This detector is currently in production and is scheduled to be operational in KATRIN in 2026.
In this talk, I will present the latest results from KATRIN on the search for keV sterile neutrinos, as well as the ongoing efforts to conduct a high sensitive search with the TRISTAN detector.

Speaker: Leo Laschinger (MPIK, TUM)

50 KATRIN++: Towards a next-generation neutrino mass experiment using tritium beta decay

After completing 1000 days of data taking at the KATRIN experiment, the collaboration expects to reach a final sensitivity on the effective anti-electron neutrino mass below 300 meV. However, neutrino oscillation observations allow the value to be as low as 50 meV or 9 meV, depending on the neutrino mass ordering. Taking the next step in direct neutrino-mass searches includes probing the region of inverted mass hierarchy and therefore requires to achieve substantial improvements in statistics, energy resolution, and background suppression.

Within the framework of KATRIN++, several novel experimental concepts are being explored to extend the sensitivity of such a next-generation experiment. Two particularly promising strategies are:
(1) the implementation of differential detection techniques with sub-eV energy resolution and
(2) the commissioning of a large-volume atomic tritium source, enabling significantly increased signal statistics. The combination of these approaches would allow for high statistics to be acquired quickly and with ultra-high energy resolution. The goal of KATRIN++ is to identify and develop the hardware technologies needed to reach the required precision. We have formed several working groups within KATRIN++ to tackle the challenges of developing new source and detector concepts. On the source side we are looking into reliable ways to produce, cool and trap tritium atoms. For the differential detection method, we are currently investigating the applicability of quantum sensor based detectors, such as metallic microcalorimeters (MMCs), as well as a Time-of-Flight based technology coupled with a Transverse Energy Compensator (TEC). Our aim is to investigate these different approaches and develop scalable technologies by mid-2030s.

In this talk, we will summarize the technological requirements and fundamental physics limitations to confine the achievable sensitivity on the neutrino mass for several experimental configurations, and present the ongoing efforts towards realising the hardware technologies inside a future experiment.

Speaker: Svenja Heyns (Karlsruhe Institute of Technology)

51 A possible solution to the gallium anomaly moving beyond the leptonic wave function factorization

For over three decades, the gallium anomaly, a persistent discrepancy exceeding 5σ between measured and predicted neutrino capture rates on gallium-71 in the GALLEX, SAGE, and BEST experiments, has challenged the particle physics community. While frequently interpreted as evidence for short-baseline sterile neutrino oscillations, this scenario is increasingly in tension with recent bounds from reactor, solar, and accelerator experiments, including KATRIN and MicroBooNE. In this contribution, we revisit the theoretical evaluation of the cross-section for neutrino capture on gallium-71. We move beyond the standard detailed-balance framework by abandoning both the conventional leading-order approximation and the strict factorization of leptonic wave functions from the nuclear matrix element. Instead, we calculate exact Dirac-Hartree-Fock-Slater wave functions for bound and continuum electron states and integrate them directly with phenomenologically constrained Gamow-Teller transition densities. By ensuring these densities accurately reproduce the precisely measured germanium-71 half-life, we are able to evaluate the full, non-factorized transition amplitude. We demonstrate that this approach yields a substantial reduction of approximately 20% in the predicted charge-current neutrino capture cross-section. Ultimately, this reduction offers a viable solution to the gallium anomaly, effectively eliminating the need to invoke physics beyond the Standard Model.

Speaker: Luca Ferro (INFN Cagliari, University of Cagliari)

52 Coffee Break

53 Non-Adiabatic Mixing in Density Matrix Formalism

Description of quantum coupling is a universal problem appearing in many different fields (NMR, quantum computing, molecular and atomic physics,...). In particle physics, it applies to particle mixing, underlying neutrino oscillations and resonant particle production (applicable beyond these two) in different environments, of great importance in many BSM scenarios. I will discuss non-adiabatic transitions in the simplest two-state coupled quantum system. An analytical description is traditionally provided by the Landau-Zener-Stuckelberg-Majorana (LZSM) approximation. However, in many applications, such as various cosmological problems, a time dependent mixing and interactions with the environment, where thermal effects and decoherence play an important role, have to be considered, requiring an extension of the LZSM approach. I will show how a density matrix formalism provides a powerful tool for treating such a problem. I will show some general analytic results that reproduce LZSM approximation in the appropriate limit but also generalise it when a time-dependent mixing is considered (decoherence can also be included, I will show results in the absence of decoherence for simplicity). I will finally comment on a comparison with existing numerical results.

Speaker: Shreya Girishkumar Pandit (University of Southampton)

54 From CUORE to CUPID: Toward a Next Generation Search for Neutrinoless Double Beta Decay

The search for neutrinoless double beta decay (0νββ) is fundamental for investigating lepton-number violation, probing new physics beyond the Standard Model, and determining whether neutrinos are Majorana particles. CUORE, a cryogenic calorimetric experiment at LNGS, studies 0νββ in $^{130}$Te using 988 TeO₂ crystals, reaching a tonne-scale mass and operating below 15 mK. Since 2017, CUORE has accumulated close to 3.0 tonne-years of exposure, constraining 0νββ in $^{130}$Te and achieving one of the most precise two-neutrino double beta decay (2νββ) half-life measurements and a detailed background reconstruction across a broad energy range. The next generation of experiments aims to probe half-lives greater than $10^{27}$ years, reaching the sensitivity required to explore the Inverted-Ordering region of the neutrino mass spectrum. CUPID (CUORE Upgrade with Particle IDentification) will search for the 0νββ decay of $^{100}$Mo, leveraging the existing cryogenic infrastructure and expertise gained from CUORE. CUPID will utilize scintillating Li₂MoO₄ crystals enriched in $^{100}$Mo, coupled with light detectors featuring Neganov-Trofimov-Luke amplification. With a total isotope mass of 240 kg, CUPID is designed to achieve a background index of 10⁻⁴ counts/keV/kg/year and a FWHM energy resolution of 5 keV. This performance will allow for a 3σ discovery sensitivity of 1.0 × 10$^{27}$ years after 10 years of life-time, corresponding to an effective Majorana neutrino mass sensitivity in the range of 12–21 meV. This work presents the latest CUORE results, recent findings from the CUPID demonstrator, and outlines the forthcoming milestones toward the realization of the CUPID experiment.

Speaker: Francesca Pucci

55 Search for the Majorana Nature of Neutrino with the LEGEND Experiment

Search for the Majorana Nature of Neutrino with the LEGEND Experiment

A. Biondi on behalf of the LEGEND Collaboration

Observation of the neutrinoless double beta (0$\nu\beta\beta$) decay would establish that neutrinos are Majorana particles and demonstrate violation of lepton number, providing a key ingredient for understanding the origin of neutrino masses and the matter-antimatter asymmetry in the Universe. As one of the most sensitive probes of physics beyond the Standard Model, the search for the $0\nu\beta\beta$ decay plays a central role in modern neutrino physics.

The Large Enriched Germanium Experiment for Neutrinoless $\beta\beta$ Decay (LEGEND) is a phased program devoted to search for the $0\nu\beta\beta$ decay in the $^{76}$Ge isotope using enriched high-purity germanium detectors operated in a low-background environment. The first phase, LEGEND-200, is taking data at the Laboratori Nazionali del Gran Sasso (LNGS) since March 2023. Following the latest upgrade, the experiment is operating 138 kg of enriched detectors, and it will employ up to 200 kg of $^{enr}$Ge in its final design. LEGEND-200 has reported its first physics results based on 61 $kg \cdot yr$ of exposure, demonstrating excellent energy resolution and very low background levels. From the collective analysis of data from GERDA, MAJORANA DEMONSTRATOR and LEGEND-200, the LEGEND Collaboration has set one of the best limits in the field on the half-life of $0\nu\beta\beta$ decay, namely $T^{0\nu}_{1/2} > 1.9 \times 10^{26}~yr$ at the 90% confidence level. It corresponds to a limit on the effective Majorana mass of $m_{\beta\beta} < 70 - 200$ meV, depending from the chosen nuclear matrix element.

The next phase, LEGEND-1000, will scale the detector mass to 1000 kg of enriched germanium while further reducing the background by an order of magnitude. With an exposure of about 10 $t\cdot yr$, it is expected to operate in a quasi background-free regime and reach a discovery sensitivity for half-lives beyond $10^{28}~yr$, covering the inverted neutrino mass ordering region.

In this talk I will provide an overview of the LEGEND program, present the latest results from LEGEND-200, and discuss the design and projected sensitivity of LEGEND-1000.

Speaker: Alex Biondi (Jagiellonian University in Krakow)

56 Beyond the Standard Model investigations at CONUS+

The detection of coherent elastic neutrino-nucleus scattering (CEνNS) opens up new opportunities for neutrino physics within and beyond the standard model (BSM) of elementary particles. The first detection of CEνNS at nuclear reactors by the CONUS+ experiment allows very valuable tests of BSM scenarios in a low momentum transfer regime. Among them, Non Standard Interactions (NSIs), light mediators (scalar and vector couplings) and electromagnetic properties were tested, setting very competitive limits in both the nuclear scattering interaction channel as well as the electron scattering channel. In particular, for vector NSIs, a sensitivity to new physics of up to 145 GeV was achieved. Whereas, for the light mediators, couplings down to $4 \cdot 10^{−7}$ were probed. Further, the Weinberg angle was constrained and found in good agreement with the Standard Model.

Speaker: Dario Piani (Max-Planck-Institut für Kernphysik)

57 The NUCLEUS experiment for Coherent Elastic Neutrino-Nucleus Scattering

Coherent elastic neutrino-nucleus scattering (CE$\nu$NS) offers a broad range of physical and technological applications. First predicted in 1974 and remained undetected until 2017, the process is currently entering the era of precision measurements. For this purpose, low energy neutrinos from nuclear reactors represent an ideal source, enabling the investigation of CE$\nu$NS in the fully coherent regime of low momentum transfer. Additionally, extremely sensitive experiments with low energy threshold and low environmental background are needed to probe the small nuclear recoil signature.

In this context, the NUCLEUS experiment is designed to detect CE$\nu$NS with antineutrinos from the Chooz nuclear power plant in France, using CaWO$_4$ cryogenic calorimeters read out by transition-edge sensors. With a demonstrated energy threshold below 20 eV and several layers of active and passive shielding, NUCLEUS aims to measure the CE$\nu$NS cross section with $\sim$20% precision during its upcoming first phase. After a successful commissioning at the Technical University of Munich (TUM), the experiment is currently being relocated to the Chooz experimental site, where a first technical run is scheduled to test a minimal version of the system. We present the milestones achieved so far and the future plans of the experiment.

Speaker: Matteo Cappelli (Sapienza Università di Roma e INFN, Roma I (IT))

Strings: Generalized symmetries & Mathematical structures in string theory and QFT

Conveners: Joseph Enea Davighi, Piotr Sułkowski (University of Warsaw)

58 Probing gluon saturation in a DIS process via nonconformal soft-wall holography

We model a soft-wall type nonconformal holography to study the gluon saturation phenomena occuring in a deep inelastic scattering process. The gravity background has been considered as a nonconformal warped version of 5D AdS geometry. The warpedness is characterized by a deformation parameter with finite length dimension. To represent a highly boosted target nucleus, we introduce a gravitational shockwave along one of the light-cone directions. The shockwave is considered to be localized along the other light cone direction. Our shockwave profile remains constant in UV regime and exponentially decays in the IR regime of the theory, thereby consistently representing a confined nucleus in IR. We propose the corresponding confinement scale as a nontrivial function of the deformation parameter. We implement specific gauge choice for the vector fields consistently with the bulk construction and solve the associated Maxwell’s field equations to deduce the current correlators of the dual nonconformal IR boundary theory. The resulting gluon structure functions are numerically found to increase and eventually saturate with the increasing deformation parameter. We comment on the emergence of a gluon saturation scale as a nontrivial function of the deformation of our bulk geometry.

Speaker: Adrita Chakraborty (AGH University of Science and Technology)

59 4d N=4 string islands from asymmetric orbifolds

String islands are isolated points in the space of string vacua that have no moduli except the dilaton, enjoy rank reduction and lead to consistent pure supergravity theories. Asymmetric orbifold constructions are powerful tools that enable us to access these points in the moduli space that are inaccessible to more standard string compactification techniques. In this talk, we classify all supersymmetry-breaking crystallographic SO(6) elements and use them to populate the landscape of type II vacua. To construct heterotic vacua, we take as orbifold actions automorphisms of the Leech lattice. In this landscape of 4d N=4 theories we identify many island candidates, explicitly construct some of them and show the appearance of archipelagos.

Speaker: Elisa Iris Marieni (University of Southampton)

60 Threading the Thimble: A Stable Route to Real-Time Path Integrals

Path integrals in real time are plagued by violently oscillatory phases, and Lefschetz thimble methods offer one of the cleanest ways to make sense of them — but only if the intersection numbers between thimbles and the original integration contour can be computed reliably. In practice, existing approaches have been limited to just one or two variables, leaving genuinely multivariable problems out of reach. I will present a stable numerical scheme that pushes this frontier dramatically. By recasting the upward flow from saddle points to the original cycle as a multiple shooting problem, the method delivers both the magnitudes and the signs of the intersection numbers, and remains well-behaved up to at least 20 variables — with quadruple precision extending its reach even further. I will apply the method to several complex saddles in a discretized real-time path integral, where it reveals new structural features of the thimble decomposition. The approach should be useful well beyond this setting, anywhere oscillatory integrals appear.

Speaker: Katarina Trailović (Institute Jožef Stefan)

61 Varieties of four-dimensional gauge theories

Given a gauge Lie algebra, it is natural to seek representations for four-dimensional spacetime fermions that are anomaly-free and chiral. However, this problem is difficult to solve in full generality. Even for irreducible representations, where we only have to study $\mathfrak{su}(n)$ for $n\geq3$, solutions would seem to be few and far between: a trial-and-error scan by Eichten, Kang and Koh found only three for $\mathfrak{su}(5)$, for example. I will explain how concepts in rational algebraic geometry show that there are in fact infinitely many anomaly-free chiral representations of semisimple algebras that are either irreducible or are products of irreducible ones. In particular, equivalence classes of these representations are in bijection with rational points on projective varieties, and all such points can be found in the above two cases. When the gauge algebra contains one extra $\mathfrak{u}_1$ summand, I will show how, while it is still possible to parameterize infinitely many solutions, it is not necessarily the case that all are found. Finally, I will give an overview of the problem of anomaly cancellation with multiple $\mathfrak{u}_1$ summands.

This talk is based on work done with Ben Gripaios in 2409.15430, 2501.09860 and 2508.11583.

Speaker: Khoi Le Nguyen Nguyen (DAMTP, University of Cambridge)

62 Quark hierarchies and spontaneous CP violation from Siegel modular forms

We consider a new flavour framework in which quark mass hierarchies naturally arise from a small departure of the modulus VEV from special stabilised regions of genus 2. By extending the modular group to this genus, the same VEV can also account for the spontaneous breaking of the assumed CP symmetry. We present for the first time a quark model which is able to fit both the mass hierarchies and the CKM matrix through a single mechanism.

Speaker: Matteo Parriciatu (Università Roma Tre)

63 Coffee Break

64 Modular and CP invariant SU(5) with a single adjoint

We consider a modular-invariant SU(5) model supplemented, for the first time, by a spontaneously broken generalized CP symmetry. Therefore, CP violation originates solely from the vacuum expectation value of the modulus, whose real component acts as the unique source of CP breaking. In the lepton sector, neutrino masses are generated via a type I+III seesaw mechanism, thanks to a single adjoint superfield, whose scalar VEV plays a role in determining fermion mass hierarchies.

Speaker: Marco Carducci (Romatre university (INFN))

65 Revisiting Instanton Effects in the Broken Phase

Instanton effects in gauge theories with spontaneously broken gauge symmetries are relevant to several phenomenological settings, including electroweak baryon-number violating processes and nonperturbative contributions to axion physics. In such theories, the relevant configurations are not exact classical minima of the action, so evaluating their effects requires some care. Earlier work pointed out a subtle difficulty in this analysis. In this talk, we revisit semiclassical instanton calculus in broken gauge theories and show how this issue can be resolved in a controlled way. We then discuss the implications for phenomenological applications. This talk is based on our recent paper, 2604.02987 [hep-th].

Speaker: Takafumi Aoki (ICRR, The University of Tokyo)

Wednesday 24 June

Cosmology

66 The James Webb Space Telescope and the Distance Network: New Paths to Understanding the Hubble Tension

One of the most basic questions in cosmology is: How fast is the Universe expanding today? Two powerful approaches give answers that should agree but do not. Measurements based on the cosmological model calibrated by the cosmic microwave background predict one value for the Hubble constant H0​, while direct measurements using the cosmic distance ladder give a higher value. The difference, now exceeding 5σ, is known as the Hubble tension and has persisted for more than a decade and challenges LambdaCDM. The James Webb Space Telescope (JWST) provides a new way to test the local distance ladder that underlies the direct measurement of H0​. By observing Cepheid variable stars and other distance indicators in galaxies that host Type Ia supernovae, and that were previously studied with the Hubble Space Telescope (HST), JWST allows a direct and independent check of those earlier measurements at higher resolution. These observations are also part of a broader effort to build a more robust local distance network, combining multiple independently calibrated distance indicators across the Milky Way and nearby galaxies. This network approach allows different rungs of the distance ladder to cross-check one another and helps expose potential systematic errors. I will review several tests of possible systematics. The JWST observations closely match the HST results across multiple methods and wavelengths, ruling out several suspected sources of systematic error and strengthening the case that the Hubble tension is real. In addition, the distance network results show that the tension does not depend on any single source, team, or sample. Rather, it may signal that something important is missing from our current picture of the Universe.

Speaker: Adam Riess

67 The H0 World Cup: Is It Coming H0me?

In this talk, I will present an updated “H0 Olympics” analysis using the latest cosmological datasets from Planck NPIPE, ACT DR6, SPT-3G, and DESI. We systematically compare twelve representative models from the recent literature, covering both early- and late-time proposals to resolve the Hubble tension. We also examine whether extensions such as a time-varying dark energy equation of state or non-zero spatial curvature improve the fit to the combined datasets or alter the apparent preference for dynamical dark energy. Compared to the 2020 analysis, current data show a stronger preference for early dark energy scenarios over other classes of solutions, with a genuine shift of $H_0$ toward higher values that is independent of late-time priors. However, even in these models, a residual tension of about $2.5$–$3\sigma$ remains, while the dynamical dark energy hint remain largely unaffected. I will conclude by discussing recent attempts to go beyond these results and the prospects for a fully satisfactory resolution.

Speaker: Dr Vivian Poulin (LUPM, CNRS & U. de Montpellier, France)

68 Dark Energy: hints of time variation?

Based on 6 years of observations and ~1,500 new high-redshift supernovae, the Dark Energy Survey (DES) team presented tentative evidence in 2024 that dark energy may be changing with time. A few months later the Dark Energy Spectroscopic Instrument (DESI) team also presented hints of time-varying dark energy, by mapping the distribution of galaxies. This talk will review the current state of evidence for the nature of dark energy, including recent updates, and discuss the implications time-dependent dark energy would have for fundamental physics and the fate of the Universe.

Speaker: Tamara Davis

Coffee Break

Particles

69 TBA

Speaker: Francesca Di Lodovico (University of London (GB))

70 MicroBooNE

Speaker: Stefan Soldner-Rembold

Group Photo

Lunch

Kelham Island Museum and Conference Dinner

Thursday 25 June

Cosmology: Neutrinos in Cosmology

Conveners: Olga Mena, Willem Elbers (Durham University)

71 Probing neutrino dark matter interactions at neutrino detectors

We study the possibility that dark matter primarily interacts with the SM through neutrinos, and the prospects for detection in neutrino detectors. In particular, we analyze the DSNB searches at Super-Kamiokande in terms of such a neutrino-dark matter interaction.

Speaker: Salvador ROSAURO-ALCARAZ (LPCA - CNRS)

72 Neutrino flavour conversion in the early universe

Neutrinos play a pivotal role in the early Universe, as their evolution and decoupling set the conditions for Big Bang Nucleosynthesis (BBN) and influence subsequent cosmological epochs. In this talk, I will focus on the effects of neutrino flavour conversion before and during the decoupling epoch, and their implications across different contexts.

While flavour oscillations have only minor effects in the standard scenario with small differences between neutrino flavours, they can become crucial in the presence of, e.g., significant lepton asymmetries. Recent developments in the treatment of neutrino quantum kinetics have enabled a more refined description of the evolution of these asymmetries, leading to new constraints and renewed interest in oscillation-driven sterile neutrino dark matter production scenarios, namely the Shi–Fuller mechanism.

Speaker: Julien Froustey (IFIC (CSIC-UV))

73 Neutrino decays in light of the neutrino mass tension

A new tension is starting to emerge between the tight cosmological upper bounds on the total neutrino mass and the lower limits from oscillation data, with potentially far-reaching implications for cosmology and particle physics. Invisible neutrino decays provide a compelling particle physics scenario to understand such measurements. In this talk, I will present updated limits on a framework where neutrinos decay non-relativistically into dark radiation, showing that the mass bound from Planck 2018+DESI BAO DR2 is relaxed to 0.23 eV, in full agreement with oscillation data. I will also report the first late-time cosmological analysis of neutrino decays into lighter neutrinos in a manner consistent with the measured measured mass splittings, showing that this scenario marginally alleviates - or even tightens - the neutrino mass bounds. These results were possible thanks to new neural network emulators, which are ~200 times faster than the full Boltzmann solutions. Based on arXiv:2601.04312.

Speaker: Dr Guillermo Franco Abellán (IFIC, CSIC - University of Valencia)

74 Limits on total lepton number and lepton flavour asymmetries from BBN and the CMB

In this talk, I will discuss the impact of lepton flavour asymmetries on BBN and the CMB. I will show that solving the momentum averaged quantum kinetic equations describing neutrino oscillations and interactions is an accurate approximation to the full momentum-dependent system. Our formalism allow us to study the scenario of total vanishing lepton number, revealing a rich flavour structure in stark contradiction to the assumption of simple flavour equilibration. We then achieve a limit on the maximal primordial total lepton number L, while specific flavour directions can be even more constrained. I will also present the publicly available COFLASY code based on our momentum-averaged formalism, which is orders of magnitude faster than similar codes which solve the full-momentum dependent system.

Speaker: Mario Fernandez Navarro (University of Zurich)

75 Origin of cosmological neutrino mass bounds: background versus perturbations

In this talk, I will address the emerging anomaly between cosmological and oscillation constraints on the sum of neutrino masses. I will review the main implications of neutrino masses at both the background and perturbations levels, discussing the primary neutrino effects to which CMB data is sensitive, and finding valuable hints to evade cosmological bounds. Our findings show that the CMB neutrino-mass bound is mostly a background measurement, i.e., how the neutrino energy density evolves with time.

Speaker: Rasmi Hajjar (CCAPP - Ohio State University)

76 Coffee Break

77 Low-Energy Neutrino Predictions from SO(10)-Inspired Leptogenesis

We discuss neutrino mass generation and Leptogenesis in GUT-motivated type-I seesaw models, focusing on the connection between matter-antimatter asymmetry and measurable low-energy neutrino parameters. Building on our study of flavour coupling, we show that spectator-induced effects can significantly reshape the viable regions in the space of the lightest neutrino mass, the Dirac CP phase, the atmospheric mixing angle, and the effective mass probed by neutrino-less double beta decay. We then present progress on an extended SO(10)-inspired framework with hierarchical Dirac neutrino masses linked to the up-quark sector. Using current neutrino data and excluding highly fine-tuned crossing-level solutions, we find that these models generically predict a strongly hierarchical right-handed neutrino spectrum and naturally realise successful N2-leptogenesis when the Dirac masses are close to the up-quark masses. This provides a unified framework linking GUT-scale neutrino physics, the cosmic matter-antimatter asymmetry, and upcoming neutrino experiments.

Speaker: Xubin Hu (University of Southampton)

78 Probing the neutrino chemical potential with cosmological observations

The electron neutrino degeneracy parameter, $\xi_{\nu_\mathrm{e}} = \mu_{\nu_\mathrm{e}} / T$, is tightly constrained by Big Bang Nucleosynthesis (BBN), while the degeneracy parameters of the other neutrino species, $\xi_{\nu_\mathrm{x}}$, remain weakly constrained by cosmological observations alone. In this talk, we present constraints on $\xi_{\nu_\mathrm{e}}$ and $\xi_{\nu_\mathrm{x}}$ using two complementary approaches: a constant free-parameter treatment to obtain physical bounds, and a model-independent reconstruction based on the Piecewise Cubic Hermite Interpolating Polynomial (PCHIP) formalism, allowing $\xi_{\nu}$ to vary with redshift and probing the origin of these bounds. We also consider two scenarios for neutrinos, specifically three degenerate neutrinos ($\xi_{\nu_\mathrm{e}}$ = $\xi_{\nu_\mathrm{x}}$) and the case in which we actually differentiate between $\xi_{\nu_\mathrm{e}}$ and $\xi_{\nu_\mathrm{x}}$. We perform a cosmological analysis combining CMB data from Planck, SPT, and ACT with BAO measurements from DESI, and reassess the results after including BBN observables from either EMPRESS, which allows for a non-zero chemical potential, or LBT, which is compatible with the standard $\xi_\nu$ = 0 prediction.

Speaker: Pietro Ghedini (IFIC, CSIC - UV)

79 Beyond thermal approximations: Precise cosmological bounds on Axion-Like Particles

We derive updated cosmological constraints on light axion-like particles (ALPs) coupled to leptons and photons using a full phase-space treatment of their production in the primordial plasma. The resulting non-thermal phase-space distributions are consistently propagated into calculations of cosmological observables, allowing a precise determination of their impact on $\Delta N_{\rm eff}$. Combining latest available CMB data with BBN measurements, we obtain $95\%$ credible limits of $f_a > 1.63 \times 10^6\,\mathrm{GeV}$, $9.41 \times 10^6\,\mathrm{GeV}$, and $8.06 \times 10^4\,\mathrm{GeV}$ for couplings to electrons, muons, and taus, respectively, and $g_{a\gamma} < 1.98 \times 10^{-8}\,\mathrm{GeV}^{-1}$ for photon couplings. Compared to astrophysical and laboratory limits, these cosmological bounds are particularly competitive for the ALP couplings to $\mu$ and $\tau$. Inclusion of baryon acoustic oscillation data mildly relaxes these bounds. We also present forecasts for future CMB experiments, discussing the importance of an exact phase-space treatment for robust constraints on ALP interactions.

Speaker: Nicola Barbieri (IFIC (CSIC-UV))

80 Listening for Right-Handed Neutrinos in Gravitational-Wave Backgrounds

I will show that spectral features of a gravitational-wave background can probe type-I seesaw parameters, independently of the gravitational-wave production mechanism. Long-lived Right-Handed Neutrinos generically induce a temporary period of early matter domination in the thermal history of the Universe, which imprints a feature in any primordial gravitational-wave background, characterised by two frequencies corresponding to the onset and end of this epoch. These frequencies are determined by the initial abundance, mass, and decay rate of the dominating species. I will explore how this mechanism is realised through non-thermal production of right-handed neutrinos in the minimal type-I seesaw, and separately the gauged $U(1)_{B-L}$ model.

Speaker: Angus Spalding (Univeristy of Southampton)

Cosmology: Cosmic Tensions

Conveners: Elsa Teixeira (Laboratoire Univers et Particules de Montpellier, University of Montpellier), William Giarè

81 From Distance Ladder to Network: Methods, Code, and Results from H0DN

The H0 Distance Network (H0DN) combines multiple distance indicators (Cepheids, TRGB, SNe Ia, SBF, megamasers, and others) into a single covariance-aware linear system to determine the Hubble constant. The baseline analysis yields H0 = 73.50 +/- 0.81 km/s/Mpc (1.09% precision, 7.1-sigma tension with early universe based inferences that assume LCDM) and demonstrates robust stability across more than 30 systematic variants. This talk will focus on the methodology: outlining the linear system of equations and covariance matrix structure underlying the generalized least-squares fit.

Speaker: Emre Ozulker

82 Dark Energy Survey Year 6: Cosmological Results and Lensing Ratios

Increasingly precise observations are beginning to expose potential cracks in the standard cosmological model, from the Hubble constant tension to emerging hints of evolving dark energy. Resolving whether these point to new physics, and uncovering the nature of dark matter and dark energy, requires precise measurements of cosmic geometry and the growth of structure. The Dark Energy Survey (DES) was designed precisely to address these questions.

In this talk, I will present the final cosmological results from DES Year 6, covering $\sim 5000 \text{ deg}^2$ with 140 million source galaxies and 9 million lens galaxies. Through the combination of cosmic shear, galaxy clustering, and galaxy–galaxy lensing ($3\times2$pt), DES Y6 yields constraints on the amplitude of matter fluctuations $S_8$ with a factor of two improvement over DES Y3. For the first time, we combine all four DES dark energy probes - $3\times2$pt, Type Ia supernovae, baryon acoustic oscillations (BAO), and galaxy clusters - into a single coherent analysis, presenting constraints in both $\Lambda$CDM and wCDM.

I will then discuss lensing ratios, an exciting geometric probe for weak-lensing cosmology. By comparing galaxy-galaxy lensing signals around the same lens sample but different source samples, the dependence on the lens mass distribution cancels, leaving a signal governed by angular diameter distances. This makes lensing ratios a clean probe of cosmic geometry and expansion history, while providing an internal validation of redshift and shear calibrations. I will show how this has already been realised in DES Y6, where lensing ratios have been used to validate photometric redshift and multiplicative shear calibrations.

Stage-IV surveys such as Euclid, Rubin/LSST, Roman and Simons Observatory, will dramatically increase statistical power, making calibration systematics ever more critical while simultaneously unlocking the full potential of lensing ratios. I will close by showing how their geometric sensitivity on small angular scales positions lensing ratios as both a precision calibration tool and a cosmological probe in their own right.

Speaker: Gisela Cristina Camacho Ciurana (ICE-CSIC)

83 A frequentist view on cosmological neutrino and dark-energy constraints

The DESI galaxy survey has recently placed the tightest constraint on the sum of neutrino masses to date. For such effects “below the detection limit”, where data can only infer upper bounds, Bayesian and frequentist methods can give important complementary information. I will begin with a short overview of the frequentist profile-likelihood method, its advantages and limitations. Using a frequentist and Bayesian toolbox, I will discuss neutrino mass constraints and the tentative evidence for evolving dark energy from recent DESI data.

Speaker: Laura Herold

84 How safe is supernovae data?

The tantalising hint of evidence for dark energy evolution depends on the interplay of data from the cosmic microwave background, baryon acoustic oscillations and Type Ia supernovae. Two recent supernovae data releases, DES-Dovekie and Union3.1, have reduced the preference for evolution compared to previous versions. What has changed? And can the data be trusted?

Speaker: Paul Shah (UCL)

85 Coffee Break

86 Disentangling cosmic distance tensions with early and late dark energy

Recent cosmological data reveal tension between parameters inferred from measurements of the cosmic microwave background (CMB), baryon acoustic oscillations (BAO), and supernovae (SN) under $\Lambda$CDM. Typical dynamical dark energy parameterizations (such as $w_0w_a$) that seek to jointly resolve these tensions have an equation of state parameter that crosses into the phantom regime, leading to potential instabilities for physical models. We show that the BAO (early-time) and SN (late-time) sides of the tension can instead be treated independently. Early dark energy (EDE) can reduce the tension between CMB-BAO data by changing the calibration of the sound horizon at the drag epoch $r_d$, with a $\Delta\chi^2 = -9.4$ relative to $\Lambda$CDM, raising $H_0$ to 70.87 $\mathrm{km \ s^{-1}Mpc^{-1}}$. EDE alone cannot bring consistency between CMB, BAO, and SN data, but combining with a thawing-quintessence component of dark energy reduces tensions between the three datasets, with $\Delta\chi^2=-12.6$ relative to $\Lambda$CDM without
a phantom component, vs.\ $\Delta\chi^2=-15.8$ for $w_0 w_a$ with one. We consider different SN datasets, using the most recent DES Dovekie catalog as our default while assessing differences with the original DESY5 and Pantheon+ catalogs. While the significance of adding thawing quintessence changes, the EDE solution to the CMB-BAO tension remains nearly unaffected. Moreover, though we do not include direct Hubble constant measurements in these $\Delta\chi^2$ values, the EDE solution reduces the Hubble tension with the Local Distance Network value from $7\sigma$ in $\Lambda$CDM to $2-3\sigma$ depending on the SN dataset, nominally the equivalent of an extra $\Delta\chi^2 \sim -40$ or more.

Speaker: Tanisha Jhaveri (University of Chicago)

87 Cosmic tensions and interacting dark energy: dynamics and observations

To address emerging discrepancies among key cosmological parameters, I investigate interacting dark sector models as a possible resolution to the persistent $H_0$ and $S_8$ tensions. I focus on scenarios in which dark matter interacts with quintessence or phantom dark energy.

I will present the background and perturbation equations for the coupled dark matter–dark energy model and discuss its constraints using a combination of low- and high-redshift observational datasets. Owing to uncertainties in both dark energy physics and current measurements, the inferred value and constraining power of the Hubble constant $H_0$ are found to be dataset dependent. Allowing the interaction parameter to vary freely, we find that while the interaction strength remains small, it is not disfavored by the data at late times. I will further compare results obtained assuming spatial flatness with those derived within a curved geometry framework. This analysis highlights the role of spatial curvature in addressing the ongoing cosmological tensions. I will delve deeper into how these findings within the Coupled+$Ω_K$ picture suggest that relaxing the flatness assumption leads to tighter and more robust constraints on both $H_0$ and $S_8$. I will also comment on the impact of different possible scalar-field potentials.

Speaker: Dr Trupti Patil (Korea Institute for Advanced Study, Seoul, South Korea)

88 Axion-dilaton interactions in the dark sector

Axion-dilaton models constitute a well-motivated and minimal class of theories that emerge in extra-dimensional completions of high-energy physics. These models naturally feature kinetic couplings between multiple scalar fields, which can have significant consequences in late-time cosmology. I will present the cosmological implications of these interactions when prescribing an axion and a dilaton field to describe dark matter and dark energy, respectively, including the predicted effects on the CMB, late time structure growth, and particle mass evolution. I will show that these effects allow a resolution of the Hubble tension and the model to fake a phantom cross, fitting the recent DESI data as well as the phenomenological parameterisations, in a single minimal framework.

Speaker: Adam Smith (University of Sheffield)

89 Towards Consistent Dark Energy Constraints from High- and Low-Redshift Probes with the Extended AP Test

Recent analyses of large-scale galaxy redshift surveys, such as those from Sloan Digital Sky Survey (SDSS) and Dark Energy Spectroscopic Instrument (DESI), as well as Type Ia supernova data, have made it possible to place meaningful constraints on the dark energy equation of state. Methods based on the Alcock–Paczynski test, which uses the clustering of large-scale structure as a standard shape, baryon acoustic oscillations (BAO) as a standard ruler, and Type Ia supernovae as standard candles all probe the recent expansion history of the Universe. These low-redshift probes consistently indicate that, in the low-redshift Universe ($z<0.8$), the dark energy equation-of-state parameter $w$ does not evolve with time, or evolves only very weakly. This behavior is consistent with that expected from a thawing quintessence field. In contrast, the Planck CMB data favors a dark energy equation of state with a mean value significantly below $w=−1$ at low redshifts and a relatively larger time variation. When adopting cosmological models that include cold dark matter and late-time dark energy, and combining constraints from CMB data with those from low-redshift probes, one obtains a seemingly contradictory result: a recent (z∼0.4) crossing of the phantom divide. If both the observational data and the analysis methods are reliable, this discrepancy between the physical properties of dark energy inferred from high- and low-redshift probes may point to limitations of the assumed cosmological model. Therefore, we extend the paradigm of cosmological models by incorporating the early DE in the current $w^{\rm CPL}$CDM models (or changes in the recombination physics) to see if one can find a model that has late-time expansion history from CMB more consistent with that from low-redshift probes. In particular, with the extended AP test, we investigate whether a unified cosmological model - simultaneously accommodating the Hubble tension through EDE and the low-redshift dark energy behavior - can bring the late-time expansion history inferred from CMB into better agreement with low-redshift probes. Preliminary results and their implications will be presented.

Speaker: Suvedha Suresh Naik (Korea Institute for Advanced Study (KIAS), Seoul, Republic of Korea)

Cosmology: Modified Gravity

Conveners: Alessandra Silvestri, Matteo Martinelli (INAF - OAR)

90 Gauge invariant perturbations of F(T,T_G) Cosmology

The Gauss-Bonnet invariant connects foundational aspects of geometry with physical phenomena in a variety of ways. Teleparallel gravity offers a novel direction in which to use the Gauss-Bonnet invariant to go beyond standard cosmology. In this work, we explore the cosmological perturbations of teleparallel gravity generalized through the Gauss-Bonnet invariant. This is crucial in understanding the viability of these models beyond background analyses. We do this by taking a gauge invariant approach, which is followed by popular gauge choice examples. It is important to take this approach to understand the stability and healthiness of the underlying theory. We determine the equations of motion for all perturbative modes and offer a physical interpretation for the new contributions for each of the modes.

Speaker: Prof. Bivudutta Mishra (BITS-Pilani, Hyderabad Campus)

91 General relativity as diffusive equilibrium of scalar-tensor gravity

Scalar-tensor theories of gravity are known to generically admit an effective imperfect fluid description, which leads to a natural interpretation of GR as a state of thermal equilibrium. In particular, it is possible to assign a temperature to nonminimally coupled fields, which increases as the theory deviates from GR. However, this temperature is conformally dependent, and can be arbitrarily tuned, threatening its interpretation as an intrinsic property of a scalar-tensor theory (as opposed to a representation-dependent property). To remedy this, we employ the frame-invariant formulation of scalar-tensor gravity, in which all quantities are manifestly independent of the choice of conformal frame. We then find that all scalar-tensor theories, not just minimal ones, feature an identically vanishing temperature. As a result, the deviation from GR is a diffusive (rather than thermodynamical) process, controlled by the frame-invariant chemical potential, and so GR emerges as the state of diffusive equilibrium in the class of scalar-tensor theories (minimal or nonminimal).

Speaker: Sotirios Karamitsos (University of Tartu)

92 A Master Equation for Screening in Luminal Horndeski Gravity

Determining the active screening mechanism from a general scalar-tensor Lagrangian remains a significant challenge when testing modified gravity models against cosmological observations. In this talk, I will present a new diagnostic framework based on a systematic study of nonlinear cosmological perturbations in luminal Horndeski theories. I will outline the derivation of a master equation for screening and demonstrate how it recovers established mechanisms, such as Vainshtein and Chameleon, directly from fundamental theory. Furthermore, this framework reveals a completely new regime we term "Phaedrus" screening, characterised by a screening radius that grows linearly with the mass of the source object. For each mechanism, I will present analytical and numerical solutions, clarifying the conditions under which they activate. Finally, I will introduce the new open-source software tools that enable this work.

Speaker: Sergi Sirera (Institute of Cosmology and Gravitation)

93 Alleviating Hubble tension with Torsion Condensation (TorC)

Persistent cosmological tensions, including the Hubble and curvature tensions, together with the theoretical challenge of unifying General Relativity (GR) with the other fundamental forces in particle theory, motivate the exploration of extensions to the $\Lambda$CDM model.
We investigate the Torsion Condensation (TorC) model, a framework derived from Poincare Gauge Theory that introduces two parameters in addition to $\Lambda$CDM. The resulting modifications can be redefined as evolving dark energy components, i.e. as a standard extension to $\Lambda$CDM model. Implementing TorC in the CAMB Boltzmann code, we perform Bayesian inference using nested sampling with PolyChord and Cobaya to compare TorC against $\Lambda$CDM. Notably, the TorC field equations are insensitive to spatial curvature. We therefore examine the implications of this "k-screening" mechanism and compare it to k$\Lambda$CDM.
We present constraints on TorC from cosmological data and assess its performance relative to $\Lambda$CDM in terms of Bayesian evidence and tension metrics, evaluating its potential to alleviate current observational discrepancies. Our results highlight the importance of exploring well-motivated extensions to GR, and of applying robust statistical frameworks when assessing their viability against precision cosmological data.

Speaker: Sinah Legner (University of Cambridge)

94 Coffee Break

95 Non-Gaussian statistics to break degeneracies in modified gravity

The characterization of the statistical properties of the cosmological density field represents a central topic in today's cosmology. Understanding the distribution of matter in the Universe provides a powerful means of testing the standard cosmological model and identifying possible deviations. Among the available probes to characterize the statistical properties of the cosmological density field, weak gravitational lensing (WL) has proven particularly effective for constraining departures from General Relativity (GR), being sensitive to the enhanced clustering of matter predicted by modified gravity (MG) theories while being largely unaffected by the uncertainties associated with galaxy bias on small scales.

Traditionally, cosmological information from the Large-Scale Structure (LSS) has been extracted through two-point statistics, such as the two-point correlation function (2PCF) and the power spectrum. However, these estimators are insensitive to non-Gaussianities arising from non-linear gravitational evolution, precisely where MG screening mechanisms are expected to operate. This limitation is especially relevant in light of upcoming Stage IV surveys, such as the Dark Energy Spectroscopic Instrument (DESI) , the Legacy Survey of Space and Time (LSST), and \textit{Euclid}.

In this work, we studied the performance of different higher-order statistics (HOS) when applied to the Hu-Sawicky formulation of $f(R)$ gravity. These models have a widely known degeneracy with the total neutrino masses that counteract the enhancement in matter clustering form MG effects. We relied on convergence maps obtained from the DUSTGRAIN-\textit{pathfinder} N-body simulations. We used both distance metrics between distributions, as well as nonparametric hypothesis tests, to assess the statistical significance of the distance between the distributions of the HOS measured on $\Lambda$CDM and $f(R)$ simulations. A common results was the HOS outperforming the 2PCF in discriminating between cosmologies, even in the presence of shape noise, which is the main source of error in this kind of analysis.

Speaker: Alessandro Vadala (INAF - Astronomical Observatory of Rome)

96 Model-independent tests of gravity with the Weyl potential evolution

Cosmological observations are well described by the LCDM model, a universe with a cold dark matter component and a cosmological constant acting as dark energy. However, more and more cosmological tensions have emerged in the past decades, putting this simple model into question. A large amount of research has focused on the quest for an alternative model of modified gravity and dark energy, but no consensus has been reached. Model-independent tests of gravity can help us to identify viable models while keeping the computational cost of data analysis minimal. In this talk, I will focus on the Weyl potential evolution, a model-independent observable tracking the combined gravitational potential Ψ + Φ. I will present a measurement of this quantity obtained using galaxy-galaxy lensing and galaxy clustering data from the Dark Energy Survey. I will also highlight how, in combination with redshift-space distortions, this new observable can help us to disentangle different alternative models.

Speaker: Nastassia Grimm (University of Portsmouth)

97 Testing modified gravity with gravitational wave lensing

Gravitational waves propagating through the universe inevitably encounter massive objects, getting deflected and magnified. The presence of lenses such as galaxies, clusters, or stars breaks the symmetries of the FLRW metric, allowing for new interactions between different polarizations. These bear the signatures of modified gravity and imprint distinctive effects on the waveforms. I will present the potential of gravitational wave lensing as a testing ground for theories beyond GR, focusing on scalar-tensor theories with screening. These are particularly interesting since screened environments naturally modify GW propagation, while evading local gravity tests. I will focus on a formalism that goes beyond the geometric optics approximation, allowing for lens-induced dispersion, which can constrain any modified theory without the need for EM counterparts.

Speaker: Dr Serena Giardino (Imperial College London)

98 Closing in on the EFTofDE with combined probes

The EFT of Dark Energy (EFTofDE) is a theoretically well-motivated class of modified gravity models, able to explain observational hints for dynamical dark energy with further testable predictions for structure growth and lensing. I will discuss the merits and challenges of combining probes of linear perturbations and present state-of-the-art constraints on the EFTofDE by combining CMB, BAO, SNe, RSD, ISW, and 3x2pt datasets. I will show that these constraints are driven not just by the constraining power of probes but also by theoretical priors. I will finally discuss how considering observables on mildly nonlinear scales from higher order terms in the EFTofDE Lagrangian can help to strengthen constraints further.

Speaker: Neel Shah (University of Portsmouth)

Particles: joint BSM and Flavour & DM experiments

Conveners: Adam Brown (University of Sheffield), Christopher McCabe (King's College London), Sarah Williams, William Barter (University of Edinburgh)

99 The SHiP/NA67 experiment at the ECN3 high-intensity beam facility at the CERN SPS

The SHiP/NA67 experiment is a general-purpose intensity-frontier experiment for the search for feebly interacting GeV-scale particles and to perform neutrino physics measurements at the HI-ECN3 (high-intensity) beam facility at the CERN SPS, operated in beam-dump mode, taking full advantage of the available $4\times 10^{19}$ protons per year at 400 GeV. The collaboration is currently optimising the experiment's initial configuration for the commissioning and first physics runs of 2032-2033.
The setup consists of two complementary detector systems downstream of an active muon shield: the scattering and neutrino detector (SND), which includes a light dark matter (LDM) neutrino target with vertexing capability. and the hidden sector decay spectrometer (HSDS), consisting of a 50 m long decay volume followed by a spectrometer, timing detector, and a PID system. BDF/SHiP offers unprecedented sensitivity to the decay and scattering signatures of various new physics models and to tau neutrino physics.

Speaker: Walter Marcello Bonivento (INFN Cagliari)

100 Searches for new physics using unconventional signatures and techniques with the ATLAS detector

Many theories beyond the Standard Model (SM) have been proposed to address several of the SM shortcomings. Some of these beyond-the-SM extensions predict new particles or interactions directly accessible at the LHC, but which would leave unconventional signatures in the ATLAS detector. Alternatively, these signatures could be relatively standard, but could benefit from unusual techniques. These analysis may require special reconstruction algorithms to be developed, enabling analysers to perform unique searches for new physics. This talk will cover several such recent searches at ATLAS.

Speaker: Sergei CHEKANOV

101 Searches for new physics using conventional signatures with the ATLAS Detector

Many theories beyond the Standard Model (SM) have been proposed to address several of the SM shortcomings, often predicting new particles which can be searched for at the LHC. This can include extended Higgs sectors, supersymmetric particles, heavy vectors or scalars, vector-like fermions, and further exotic particles. This talk will cover several related searches, focusing on prompt topologies and conventional analysis techniques.

Speaker: Selaiman RIDOUANI

102 CMS Prompt BSM

103 Coffee Break

104 CMS Long-lived BSM

105 Searches for Dark Matter with the ATLAS Experiment at the LHC

The presence of a non-baryonic Dark Matter (DM) component in the Universe is inferred from the observation of its gravitational interaction. If Dark Matter interacts weakly with the Standard Model (SM) it could be produced at the LHC. The ATLAS Collaboration has developed a broad search program for DM candidates in final states with large missing transverse momentum produced in association with other SM particles (light and heavy quarks, photons, Z and H bosons, as well as additional heavy scalar particles) and searches where the Higgs boson provides a portal to Dark Matter, leading to invisible Higgs decays. The results of recent searches on 13 and 13.6 TeV pp data from the LHC, their interplay and interpretation will be presented.

Speaker: Bernardo Ricci

106 Dark Matter Searches at PICO

The PICO collaboration operates bubble chambers to search for WIMP dark matter, leveraging the excellent gamma rejection and long live fractions enabled by operating at a lower degree of superheat than the bubble chambers of the 1960s. This advancement allows for significantly improved background rejection while maintaining sensitivity to nuclear recoils. Located at the SNOLAB underground laboratory, these detectors use fluorinated target fluids optimized for probing spin-dependent WIMP-proton interactions. Previous experiments, PICO-2L and PICO-60, set the world’s strongest constraints on spin-dependent WIMP-proton scattering. The next-generation detector, PICO-40L, is now fully operational and actively collecting physics data. Its superheated C3F8 target provides an ideal medium to achieve world-leading sensitivity in this search. This talk will provide an overview of the detector design, analysis strategy, and initial physics results. Looking ahead, PICO-500, a 250-liter chamber currently in development, is expected to begin commissioning in 2026, further advancing the search for dark matter.

Speaker: Dr Mayank Tripathi (mtripathi@uchicago.edu)

107 Recent results from XENONnT

The XENONnT experiment operates a liquid xenon time projection chamber at the INFN Laboratori Nazionali del Gran Sasso, designed to search for weakly interacting massive particles (WIMPs). Its ultra-low background rate and low energy threshold, achieved to maximize WIMP sensitivity, also enable the study of other rare processes.

In this talk, I will present the latest results from XENONnT. A search for spin-independent WIMP–nucleon interactions based on a 3.1 tonne-year exposure sets new constraints for WIMP masses above $10 \text{ GeV}/c^2 $. In addition, recent results on coherent elastic neutrino–nucleus scattering (CEvNS) from solar $^{8}\text{B}$ neutrinos demonstrate sensitivity to this low-energy signal and probe the neutrino background relevant for future dark matter searches.

Speaker: Sana Ouahada (University of Zurich)

Strings: Black Holes

Conveners: Arash Ardeali, Marina David

108 Black hole resonances under perturbation: a dynamical system

The quasinormal mode (QNM) spectra of black holes have been studied since the 1970s. In 2015 the imprint of the fundamental quadrupolar QNM was observed in the gravitational-wave signal from a binary merger. QNM (and Regge-pole) resonances have a local dependence on the potential maximum associated with the black hole light-ring, and also a global dependence on boundary conditions. In this talk we investigate how the resonance spectrum can be strongly disrupted by a weak perturbation in the potential (the Elephant-and-Flea phenomenon). For the case of delta-function perturbation of strength A, we formulate a dynamical system in which resonances follow continuous trajectories with A in the complex plane. We define attracting and repelling points for this dynamical system. The repelling points typically lie close to the unperturbed QNM frequencies, leading to extreme sensitivity in the spectrum to A (i.e. failure of linearised approximations even for tiny values of A). These repelling points appear to be closely related to the Exceptional Points identified by Motohashi (arXiv:2407.15191) which are associated with avoided-crossings of resonances (cf. level-repulsion in quantum mechanics) and enhanced mode contributions in the time-domain (Macedo et al, arXiv:2512.02110). This talk is based on work with T. Torres and arXiv:2601.04892.

Speaker: Sam Dolan

109 Evaporating black holes: how the burden of their memory stabilizes them

The memory burden effect describes how an object's stored information resists its own decay. This mechanism is especially pronounced in saturons—systems that saturate unitarity bounds on entropy—with black holes providing the prime example. I will show how memory burden can halt Hawking evaporation and dynamically stabilize black holes against complete decay. Crucially, this phenomenon is not exclusive to gravity: it arises naturally in generic quantum many-body systems and renormalizable field theories, underscoring its broader theoretical relevance. I will then discuss the phenomenological consequences, focusing on potential signatures in the early Universe and today. In particular, memory-stabilized black holes can produce distinctive high-energy cosmic-ray signals and leave characteristic imprints on the CMB, offering correlated cosmological and astrophysical probes of this peculiar form of dark matter.

Speaker: Michael Zantedeschi

110 Quantum Solitons and Non-Perturbative Backreaction in AdS₃

I will describe a new class of semiclassical geometries capturing the quantum backreaction of thermal conformal fields in three-dimensional anti-de Sitter space. These “quantum solitons” arise from placing a brane in the four-dimensional AdS C-metric. From the brane perspective, the construction gives solutions of three-dimensional gravity coupled to a strongly coupled holographic CFT. The resulting geometries fall into two families labelled by the asymptotic mass: one describes the backreaction of a thermal CFT state on global AdS₃, while the other exhibits a novel non-perturbative effect in which a black hole horizon present in the zero-backreaction limit is replaced by a smooth origin. I will give an overview of the construction of these solutions, their physical interpretation, and their relation to existing three-dimensional braneworld constructions.

Speaker: Robie Hennigar

111 Numerical Relativity in effective field theories of gravity

I will discuss how Numerical Relativity can serve as a tool to study non-linear dynamics in effective field theories (EFTs) of gravity. I will first present our work on scalar-Gauss-Bonnet gravity, in which a change of gauge enables well-posed evolutions in black hole spacetimes, which reveal potential smoking gun signatures in gravitational-wave emission. I will then introduce a recently proposed well-posed formulation by Figueras, Held and Kovács that applies to all polynomial higher-derivative EFTs of gravity and show our initial progress in exploring dynamical Chern-Simons gravity.

Speaker: Llibert Aresté Saló

112 Coffee Break

113 Volume as Time: Boundary Dynamics Near Black Hole Horizons

Different notions of time arise from different choices of observer. In cosmological settings, a particularly natural choice is the spacetime volume, which is conjugate to the cosmological constant. This gives rise to unimodular time, deparametrizing the Wheeler–DeWitt equation into a Schrödinger-like evolution equation. I will first explain how this construction appears in arbitrary dimension, with particular emphasis on the four-dimensional case.

As an explicit Holographic realisation, I will then focus on near-extremal black holes, whose low-energy throat dynamics is universally described by Jackiw–Teitelboim gravity. In this setting, promoting the vacuum cosmological constant to a dynamical top-form degree of freedom provides a bulk clock in the Henneaux–Teitelboim sense. Holographically, this modifies the usual Schwarzian boundary dynamics by coupling it to an additional U(1) phase mode, reproducing the universal low-energy structure familiar from complex SYK. Finally, I will show that the resulting boundary theory can be rewritten as a (0+1) dimensional observer action, making explicit the relation between the bulk volume clock and its holographic boundary counterpart.

Speaker: Farbod-Sayyed Rassouli (University of Nottingham)

114 Detecting black hole microstates

A step towards probing the black hole interior and its structure is being able to detect the black hole microstate. We demonstrate that the Euclidean two-point function of an appropriately chosen probe operator can detect the microstate of an asymptotically AdS black hole. This detection, which requires a tuned, state-dependent choice of probe, is the result of a new gravitational saddle, which dominates over the usual saddles. The gravitational result can be explicitly reproduced in the dual boundary CFT if we assume the eigenstate thermalization hypothesis. We also discuss a binary search protocol to detect the black hole microstate from a candidate list.

Speaker: William Chan (University of Pennsylvania)

115 Tidal Love Numbers of Black Holes Dressed by Dark Matter

Tidal Love numbers (TLNs) encode the deformability of compact objects under external tidal fields and leave observable imprints in gravitational wave signals. While black hole TLNs vanish in vacuum general relativity, the presence of surrounding matter can alter this picture. This talk presents a study of the axial (magnetic) TLNs of a Schwarzschild black hole embedded in a spherically symmetric dark matter distribution, modeled as an anisotropic fluid with three astrophysically motivated density profiles: Einasto, Hernquist, and NFW. Analytic closed-form expressions are derived via a small-compactness expansion and benchmarked against direct numerical integration of the perturbation equations. A key finding is that profiles without compact support generically produce logarithmic terms in the asymptotic expansion of the perturbation variable, obstructing the standard tidal matching procedure and pointing to the subtleties of defining tidal observables for black holes dressed by matter. The broader implications for gravitational wave detectability with next-generation detectors are discussed, highlighting dark matter environments around compact objects as a promising multi-messenger target.

Speaker: Simone D'Onofrio (ICE - CSIC)

116 Love for Quantum Black Holes

We investigate quantum corrections to the tidal Love numbers of near-extremal Reissner-Nordström black holes. In the near-extremal regime, the black hole develops a long AdS2 throat whose low-energy dynamics are governed by the Schwarzian action and whose quantum fluctuations become parametrically large at low temperatures. We consider the tidal response to an external scalar field probing the mouth of this throat and compute the quantum-corrected Green's function, extracting both static and dissipative Love numbers. We find that the scalar Love numbers do not vanish, to all orders in ℏ, providing a non-trivial quantum extension of the classical result.

Speaker: Marina David

Lunch

Particles

117 TBA

Speaker: Prof. MARTIN BAUER (IPPP Durham)

118 Latest results from the NA62 experiment

The NA62 experiment at the CERN north area was designed and built to study the $K^{+}\rightarrow\pi^{+}\nu\bar{\nu}$ decay. The $K^{+}\rightarrow\pi^{+}\nu\bar{\nu}$ decay is a golden mode for flavour physics, and became the rarest decay observed with a significance above 5 sigma following the NA62 measurement of \mathcal{B}(K^{+}\rightarrow\pi^{+}\nu\bar{\nu})=(13.0^{+3.3}_{-3.0})\times10^{-11}$ using 2016–2022 data. A new measurement, from the analysis of the 2023–2024 dataset is presented. With the performance needed to study the ultra-rare $K^{+}\rightarrow\pi^{+}\nu\bar{\nu}$ decay, the NA62 experiment is able to cover a broad physics program. A selection of the latest results from this program are presented including: precision measurements of kaon decays, studies rare kaon decays and searches for exotic states.

Speaker: Dr Joel Swallow (INFN - Laboratori Nazionali di Frascati)

119 Measurement of the ratios $R(D^{(*)}) = \mathcal{B}(B \to D^{(*)} \tau \nu) / \mathcal{B}(B \to D^{(*)} \ell \nu)$, using semileptonic tagging and leptonic $\tau$ decays with the $BABAR$ detector

Semileptonic decays of $B$ mesons involving $\tau$ leptons are sensitive probes for physics beyond the Standard Model. The relative rates of the branching fractions $R(D) = \mathcal{B}(B \to D \tau \nu) / \mathcal{B}(B \to D \ell \nu)$ and $R(D^*) = \mathcal{B}(B \to D^* \tau \nu) / \mathcal{B}(B \to D^* \ell \nu)$, where $(\ell=e,\mu)$ are independent of the CKM element $|V_{cb}|$ and many theoretical uncertainties. We report a measurement of ratios $R(D)$ and $R(D^{*})$ using semileptonic $B$-tagging and leptonic $\tau$ decays using the 433 fb$^{-1}$ data collected at the $\Upsilon(4S)$ resonance by the $BABAR$ detector at the PEP-II collider located at the SLAC National Accelerator Laboratory.

Speaker: Fergus Wilson (Science and Technology Facilities Council STFC (GB))

Coffee Break

Strings

120 Entropy of near-extremal and near-BPS black holes in AdS_3 supergravity.

In this talk, I will discuss the behaviour of the Euclidean path integral at low temperatures in the context of AdS_3 supergravity, highlighting the difference between near-extremal and near-bps limits. In our work, we analyzed quantum fluctuations in both the near-horizon and asymptotic regions and clarified various aspects of the bosonic fluctuations (namely, the rotational modes and gauge modes) that have been confusing in the literature. We highlight the role of boundary conditions in AdS_3, and show in particular that the gravitational path integral in the near-horizon region is inequivalent to that around the full BTZ solution at low temperature.

Speaker: Diksha Jain

121 TBA

Speaker: Luigi Tizzano

Public Talk

Convener: Adam Riess

Friday 26 June

Cosmology: Dark Energy

Conveners: Laura Herold, Supriya Pan

122 Viable interactions in the dark sector

Extensions of $\Lambda$CDM with interactions between dark matter and dark energy are a promising route to address the current cosmic tensions. In this talk, I will discuss interacting dark sector models with entropy couplings, which give rise to pure-momentum transfer in cosmology. While the background evolution is unchanged, the models are characterised by distinct observational signatures at the level of cosmological perturbations. I show that the couplings lead to a late-time suppression of structure growth while remaining compatible with CMB measurements, which is especially relevant for addressing the $S_8$ tension. I will then discuss the theoretical viability of these types of interactions and observational constraints from current survey data.

Speaker: Erik Jensko (University College London)

123 Momentum-transfer coupling between dark matter and early dark energy

Early Dark Energy (EDE) is a well-studied extension of ΛCDM
proposed to address the Hubble tension. In these models, a new dark
energy component, typically described by an axion-like scalar field,
becomes dynamically relevant at early times and then rapidly dilutes
around matter-radiation equality, leaving a negligible contribution to
the late-time energy budget. Throughout this active phase, EDE can raise
the CMB-inferred value of the present expansion rate by reducing the
sound horizon before recombination. However, in its simplest form, EDE
typically requires a larger physical dark matter density and therefore
worsens the S8 tension with weak-lensing measurements. In this talk, I
will present a model in which cold dark matter is coupled to an
axion-like EDE field through a pure momentum-transfer interaction. This
class of coupling is known to preserve the background conservation of
the dark matter energy density, while modifying the dark matter Euler
equation and the EDE perturbations. Using recent cosmological data I
will discuss the implications of momentum-transfer interactions for a
single EDE field to simultaneously resolve both the H0 and S8 tensions.

Speaker: Elsa Teixeira (Laboratoire Univers et Particules de Montpellier, University of Montpellier)

124 Reconstructing dark energy with few assumptions

Baryon acoustic oscillation (BAO) measurements from the Dark Energy Spectroscopic Instrument (DESI) strengthen the cosmological evidence for dark energy beyond the cosmological constant to the ~3σ level when combined with cosmic microwave background (CMB) and Type Ia supernovae (SNe Ia) observations. This evidence is obtained assuming a dark energy equation of state restricted to linear order in the scale factor, and an active area of research is determining how this restriction affects the data’s preferences. Dark energy “reconstructions” take a data-driven approach, describing dark energy’s properties with flexible functions that have fewer restrictions on the possible forms of evolution. We parametrize the dark energy equation of state and energy density using piecewise constant functions of redshift, effectively inferring these functions’ averages within seven redshift bins from $z=0$ to $z=4.2$. Across six different BAO and SNe Ia dataset combinations—with BAO from DESI and the Sloan Digital Sky Survey (SDSS) alongside the latest, recalibrated SNe Ia samples—we find local deviations from $\Lambda$CDM with significance up to ~3σ in the energy density and ~2σ in the equation of state. Our results are broadly consistent with linear evolution and indicate a tentative phantom crossing, most clearly manifesting as a local maximum in the dark energy density.

Speaker: Daniel A. Kessler (University of Sheffield)

125 Non-Linear Effects of the Interacting Dark Energy Model

We focused on a phenomenological interacting dark energy model (IDE) with energy-momentum transfer from dark matter to dark energy through a coupling $Q = ξ\mathcal{H}ρ_{DE}$. Following our previous work on constraining the parameters of the same IDE model using CMB and DESI data, we now present the N-body simulation results based on a modified version of RAMSES code. Compared with the fiducial LCDM results, the IDE model predicts an enhanced power on large scales but suppressed clustering on small scales (k ≥ 2 h/Mpc), consistent with the reduced dark matter density at late times.

Speaker: Yuejia Zhai (University of Sheffield)

126 Early- and Late-Time Dark Energy Dynamics after DESI

In this talk, I will discuss how recent DESI results may reshape our understanding of the dark energy sector. I will focus on the emerging preference for late-time dynamical dark energy and its possible connection with early-time components active before recombination, often invoked to address the Hubble tension. I will ask whether early- and late-time dark energy require distinct extensions of ΛCDM, or whether they can emerge as different manifestations of the same underlying dark-sector dynamics.

Speaker: William Giarè

127 Coffee Break

128 Unveiling the Dark Universe with the Sun

The sun is a powerful tool for investigating the dark universe. In the core of the sun light scalar particles can be produced via Primakoff process in the electric field of the ions and via the intense magnetic field. There can also be production vis the magnetic field in the tachocline. This allows for stringent constraints on new scalar particles which could play the role of dark energy. This will be discussed

Speaker: Anne Davis

129 Beyond LCDM: Dynamical Dark Energy and High-Redshift Reionization

This talk will explore deviations from the standard cosmological model across cosmic history. First, I will present data analysis results on dynamical dark energy using a novel pressure parametrization and four parameters parametrization testing by the latest datasets. Second, I will discuss model-independent reconstructions of the reionization history using Gaussian processes. We utilize these reconstructions to place robust bounds on exotic energy injections and decaying particle models.

Speaker: Hanyu Cheng

130 Cosmological signatures of a solidly unified dark sector

I will present a cosmological model with a unified solid dark sector that transits from a CDM phase at high redshift to a quasi-de Sitter phase at late times. Remarkably, this can be accomplished without generating strong acoustic oscillations, thus being compatible with observations of the matter power spectrum. The solid unified dark sector can reduce the rate of matter clustering in the late universe compared to the standard $\Lambda$CDM scenario, providing potential ways to alleviate the σ8 tension. A distinctive signature of the model is the generation of a non-trivial slip parameter that could be imprinted in weak lensing measurements. Additionally, gravitational waves acquire a nonvanishing mass term due to the shear distortions.

Speaker: María Pérez Garrote (Universidad de Salamanca)

131 A QCD vacuum motivated model of dynamical dark energy

The nature of dark energy has been a growing point of debate in recent years, particularly after the DESI measurements of the Baryon Acoustic Oscillations. While frequentist metrics appear to indicate a growing preference for a dynamical dark energy, some bayesian approaches indicate otherwise. Beyond this, there also lies the question of whether there exists a physical motivation behind any phenomenological parametrisation of dynamical dark energy.
The model described in this talk is motivated from computations of the non-perturbative QCD vacuum, which we parametrise into a dynamic, non-local contribution to the energy density, described by two additional cosmological parameters. I will describe how this model compares against both CPL and ΛCDM on the latest cosmological datasets, employing both frequentist χ² statistics and Bayesian model comparison. For the latter, the evidence is estimated from MCMC chains via the learnt harmonic mean estimator method which bypasses the need for the computationally expensive, nested sampling to obtain estimates of the evidence.

Speaker: Dong Ha Lee (University of Sheffield)

Cosmology: Dark Matter in cosmology

Conveners: Clare Burrage (University of Nottingham), Laura Covi (Georg August Universitaet Goettingen (DE))

132 break

133 Constraining cosmology with the Lyman-alpha forest

The Lyman-alpha forest is a powerful cosmological probe of matter density fluctuations in the weakly non-linear regime through the high redshift and underdense intergalactic medium (IGM). The most commonly used statistic to characterize these fluctuations is the 1D flux power spectrum. On small scales, the Lyman-alpha forest traces the properties of dark matter, encoding information on its still unknown nature. At the same time, the flux power spectrum is sensitive to complex gas dynamics arising from IGM photoheating during reionization. As such, the Lyman-alpha forest provides constraints that are complementary to other probes, such as the CMB. In this talk, I will present recent constraints on Cold+Warm Dark Matter (CWDM), in which structure growth is affected by the free-streaming of the warm component, using the Sherwood-Relics simulation suite and high signal-to-noise ratio, high-redshift spectra from UVES and HIRES spectrographs. These results highlight how small-scale features in the forest reveal fundamental aspects of both dark matter and the IGM thermal history.

Speaker: Olga Garcia Gallego (Institute of Astronomy, University of Cambridge)

134 Relaxing Lyman-$\alpha$ bounds by self-cooling Dark Sectors

Light dark matter is usually constraint by large-scale structure observations via Lyman-$\alpha$ lines to $m_\text{DM}\gtrsim \mathcal{O}(5\text{keV})$. I will discuss how these bounds can be relaxed for dark sectors which are produced non-thermally from the SM bath but cool themselves via $2\leftrightarrow3$ "cannibal" reactions.
Thermodynamic predictions of this cooling are in many regions outweighed by the combined effect of dark sector depletion via decay to DM and simultaneous regeneration via inverse cannibal ($2\to3$) reactions.

In numerical studies, bounds are found to relax as low as 1keV even in simplistic SM extensions of only a cannibalizing scalar and a DM fermion. The cooling mechanism also works for dark sectors consisting of dark gauge bosons of a broken non-Abelian gauge symmetry SU(N), which naturally hosts cannibal reactions.

The models demonstrate a sizable relaxation of Lyman-$\alpha$ bounds, as well as the possibility to implement self-cooling mechanisms in wide-spread SM extensions without the need for uncommon ingredients.

Speaker: Stefan Lederer (NCBJ)

135 UV, IR, and inflaton driven Freeze-in

We investigate a scenario in which the dark matter is produced via freeze-in with contributions from both the UV and IR. We also take into account an additional production mode from the decay of the inflaton. We analyze the parameter space at the level of the dark matter phase space distribution to assess potential impact of a non-thermal distribution, including bounds from Lyman-$\alpha$ measurements.

Speaker: Dimitrios Karamitros (University of Padova & INFN Padova)

136 Thermal effects on Dark Matter production during cosmic reheating

The relic abundance of Dark Matter (DM) produced via thermal freeze-in is sensitive to the thermal history during and after cosmic reheating. In minimal models, this opens up the possibility to make predictions for collider observables by combining the requirement to match the DM relic abundance with observations of the Cosmic Microwave Background (CMB). We assess the impact of thermal corrections to the rate of cosmic reheating and the rate of thermal DM production on CMB observables and the relic abundance. We find that such corrections are generally small in the regime where they can be computed by means of finite-temperature field theory. We construct counter-examples where this general rule is violated.
Talk based on arXiv:2604.16085.

Speaker: Yannis Georis (Kavli IPMU)

137 Coffee Break

138 Flipped rotating axion: Baryogenesis and Dark Matter

It is shown that the co-genesis of baryon asymmetry and dark matter can be achieved through the rotation of a spectator axion-like particle, because of a flip in the vacuum manifold’s orientation at the end of inflation. This can occur if the axion has a periodic non-minimal coupling to gravity (while preserving the discrete shift symmetry) in non-oscillating inflation models, where the inflaton field is characterised by a runaway potential. Our rotating axion can generate the baryon asymmetry of the Universe through spontaneous baryogenesis, while at a later epoch it can oscillate as dark matter. We show that in order to avoid fragmentation of the axion condensate during the rotation, we require the non-minimal coupling ξ ∼ (f/m_P)^2, where f is the axion decay constant.

Speaker: Prof. Konstantinos Dimopoulos (Lancaster University)

139 Screened Forces in a QCD-like Dark Sector on Galactic Scales

Persistent small-scale challenges to the ΛCDM cosmological model have motivated the consideration of dark matter models with richer phenomenology. We consider a dark QCD scenario in which dark axions mediate a screened force between dark baryons within dark matter halos. Finite-density corrections to the dark QCD quark condensate introduce a density-dependent interaction term between dark axions and dark baryons, with a $\mathbb{Z}_2$ symmetry breaking, analogous to the symmetron mechanism. We use the FIRE-2 cosmological simulations, spanning dwarf to group halo mass scales, to test the feasibility of realistic dark matter halo profiles sourcing the dark axion. Through multi-objective optimization, we identify 3 example parameter sets that produce attractive forces of order $\sim 1-5$ times the strength of gravity, active over distances ranging from $\sim 50$ kpc to $\sim 1$ Mpc from the center of the halo, or $\sim 0.2 R_{\rm Vir}$ to $\sim 5 R_{\rm Vir}$ for a Milky Way-like halo. The force profiles generally follow the same structure: a screened center, a transition region where the force is active, and an outer decay to zero. Though our results only reflect the instant in which the axion is sourced, we tested this model against dynamical stability criteria including the free-fall time scale and Jeans length. These predict a spherical shell around the halo, aligning with the peak of the force profile, where circular orbits may be unstable and the halo is more vulnerable to collapse. The free-fall time is also lowered, suggesting that this DM model will result in large-scale rearrangement of the dark matter density.

Speaker: Mathilda Denison (University of Pennsylvania)

140 Gravothermal evolution of dissipative self-interacting dark matter halos

Many proposed self-interacting dark matter (SIDM) models give rise to radiative processes that can dissipate energy from dark matter halos. We present the first extension of the N-body formalism for frequent small-angle self-interactions (fSIDM) that includes effective dissipation.
We find that dissipation qualitatively changes the gravothermal evolution of SIDM halos beyond simply accelerating collapse. Sufficiently strong central cooling can invert the usual role of heat conduction: the formation of an isothermal core is suppressed such that conduction remains directed inward throughout the evolution. Meanwhile, outer halo regions can cool efficiently, leading to enhanced mass infall and distinct final density profiles. These effects depend strongly on the cooling rate but are comparatively insensitive to the angular dependence of the self-interaction cross section.
Our results reveal new dynamical behavior of dissipative SIDM and open a route to connecting halo structure and recently reported dark compact objects to dark-sector microphysics.

Speaker: Ludwig Schmidt (Technical University of Munich)

141 X-ray femtolensing probes asteroid-mass black holes

The asteroid-mass regime is the key remaining window in which primordial black holes could constitute all of dark matter. I will present a new method to probe a substantial portion of this window using X-ray femtolensing. While photometric microlensing requires long observations of very stable compact sources, the energy-dependent features imprinted onto X-ray spectra furnish a clean target with relatively little in the way of astrophysical backgrounds. I will demonstrate that that per-event fringe detection is straightforward for asteroid-mass objects lensing bright compact Galactic sources, meaning that the only bottleneck is the lensing event rate. Remarkably, the ~35 megaseconds of archival data already in hand from RXTE and NICER are sufficient to probe PBH dark matter at masses of order $10^{19}\,{\rm g}$ with existing data. I will further explain how upcoming data will make these bounds substantially more robust even without any dedicated searches.

Speaker: Benjamin Lehmann (Massachusetts Institute of Technology)

Particles: Beyond the Standard Model & Flavour Physics

Conveners: Sarah Louise Williams (University of Cambridge (GB)), William Barter (University of Edinburgh)

142 break

143 CPV in Heavy Flavour decays

Speaker: Linxuan Zhu

144 TBA

145 Measuring the neutron Electric Dipole Moment for CP-violation searches beyond the standard model.

The n2EDM experiment aims to measure the neutron Electric Dipole Moment (EDM) with an unprecedented precision of $10^{-27} \, e$ cm.
The EDM is the interaction between the neutron spin and an external electric field. It is measured via precession frequency measurements on stored ultracold neutrons.
A better measurement of the nEDM probes CP-violation Beyond the Standard Model and allows for better constraints on the processes leading to matter-antimatter asymmetry.
This talk will present the status of the n2EDM experiment which will start data-taking at the Paul Scherrer Institute (Switzerland) in summer 2026.

Speaker: Katia MICHIELSEN (LPSC, Grenoble)

146 Coffee Break

147 Cosmic Millicharged Background, Reheating, and Arithmetica Electrōrum

I will discuss the cosmic relic background of millicharged particles—hypothetical particles with electric charges much smaller than the electron’s—that may have been produced in the early universe and left an irreducible relic today. I will explain how experimental searches for these particles can provide novel probes of reheating cosmology, the poorly constrained epoch immediately after inflation that determines the temperature and particle content of the primordial universe. Finally, I will touch on a fundamental mathematical issue in millicharge phenomenology related to the theoretical consistency of fractional charges and their embedding within gauge theories and cosmological models.

Speaker: Yu-Dai Tsai (University of California, Irvine)

148 An exploration of the NMSSM using deep learning to fit hints of new scalars

In this talk we discuss a recent search over the parameter space of the Next-to-Minimal Supersymmetric Standard Model using deep learning techniques. The particular focus of this search is identifying parameter values that explain hints of excesses around 95 GeV and 650 GeV in Higgs studies, and a discrepancy in Electro-Weakino searches, as well as predicting mono-H and mono-Z signatures of dark matter. For this study we employ a recent scanning tool called DLScanner. This tool uses deep learning techniques to efficiently identify parameter regions that accommodate a number of constraints consistent with current observations as well as the mentioned scalars and Electro-Weakino. Furthermore, we present evidence of parameter values with promising possibilities for phenomenological studies.

This talk is based on "Explaining data excesses over the NMSSM parameter space with Deep Learning techniques" (JHEP 02 (2026) 077) by A. Hammad, Raymundo Ramos, Amit Chakraborty, Pyungwon Ko, and Stefano Moretti.

Speaker: Raymundo Ramos (Korea Institute for Advanced Study)

149 Vector Resonances at Muon and Wakefield Colliders

We explore the potential of future high-energy lepton colliders to probe heavy vector resonances.
At wakefield colliders, intense beam-beam interactions produce radiation, called beamstrahlung,
which redistributes luminosity from the nominal energy across a broad spectrum of lower collision
energies. We show that this effect, conventionally viewed as a drawback, dramatically enhances
sensitivity to resonances by effectively scanning a wide range of center-of-mass energies. We present
projections for a benchmark scenario of a heavy kinetically mixed Z′.

Speaker: Massimo Cipressi (SISSA)

150 Slow force carriers in particle physics and cosmology

I show that gauge theory and gravity admit local modifications in which all local symmetries are broken, leading to new gapless modes universally coupled to matter. The new modes have small speed, which suppresses all their interactions with matter, making them compatible with current observations. No new scales or fundamental fields are introduced in this approach, as the new physical modes are the longitudinal components of standard force carriers. The new slow forces provide a conservative channel of new physics beyond the standard model of cosmology and particle physics, as well as a consistent and minimal framework to explore approximate gauge symmetry and departures from relativity. I discuss the phenomenology of these new slow forces in the context of cosmology, astrophysics, and particle physics.

Speaker: Francesco Serra (Johns Hopkins University)

Particles: Higgs & Electroweak

Conveners: Chris Hays (University of Oxford (GB)), Peter Millington (University of Manchester)

151 Higgs boson production and decay rate measurements with the ATLAS experiment

With the Run 2 and Run 3 pp collision dataset collected by the ATLAS experiment at LHC, very precise measurements of Higgs boson production and decay rates can be performed, shedding light over the electroweak symmetry breaking mechanism. This talk presents the latest precise measurements of Higgs boson productions and decays, including fiducial, differential, as well as Simplified Template Cross-section (STXS) measurement results, from the ATLAS experiment.

Speaker: Ahmed MARKHOOS

152 V-associated production & vector boson fusion of Higgs bosons as an LHC signature of CP violation

Many well-motivated extensions of the Standard Model predict new, entirely bosonic sources of CP violation (CPV). In these scenarios, the simultaneous observation of carefully selected bosonic processes emerges as a simple yet powerful method to unambiguously reveal the presence of CPV. The present study, which establishes a promising framework of CPV searches for the upcoming HL-LHC era, showcases this method by exploring the detectability of such generic CPV signatures within the economical Complex Two-Higgs Doublet Model (C2HDM). Specifically, we assess the observation prospects for viable combinations of gluon fusion, vector boson fusion and V-associated production processes which unequivocally signal the existence of CP-violating couplings within the bosonic spectrum of the model. Finally, we discuss an ongoing extension of this work which completes the framework through the exclusive use of gluon fusion processes.

Speaker: Álvaro Lozano Onrubia (IFT UAM-CSIC & Universidad Autónoma de Madrid)

153 Natural Higgs mass from power-law running

We revisit the renormalization of the Higgs mass using on-shell scheme. It is mass-dependent scheme and threshold correction is automatic. It clarifies that the renormalized Higgs mass $m^2(q^2)$ runs quadratically in the external momentum $q^2 \log q^2$ and the ratio $m^2(q^2)/q^2$ is order one up over all scale. The light Higgs mass is naturally explained by order one relation at the unification scale, without fine-tuning.

Speaker: KAng-Sin Choi (Ewha Womans University)

154 Higgs Criticality: Electroweak Vacuum Metastability as a Window to Beyond the Standard Model Physics

This work proposes a direct link between the hierarchy problem and Weakly Interacting Massive Particles (WIMPs): we suggest that the small mass of the Higgs boson arises from being dynamically driven to the scale of the WIMP. Such a special electroweak vacuum is singled out by lying close to the critical boundary of a phase transition, as recently explored in a new class of cosmological solutions to the hierarchy problem. They generically predict the Higgs potential to be destabilised just above the weak scale. Intriguingly, the requirement for new physics to achieve this coincides with two independently well-motivated expectations: a split spectrum of light fermions and heavy bosons, as anticipated from naturalness, and the so-called "WIMP miracle". A WIMP with mass around the weak scale not only happens to have the correct thermal relic abundance to be the dark matter (DM), it can also give rise to the necessary critical boundary at the TeV scale through its Yukawa couplings to the Higgs. We use a higgsino-like singlet-doublet model to illustrate our Higgs-DM criticality scenario and show that if this WIMP DM mass is observed to be greater than ~1.2 TeV then it necessarily implies a strong bound on the Higgs mass and an upper bound on the scale of heavy new physics that restores vacuum stability. It can be thoroughly probed in direct detection experiments, astrophysical signals and future collider searches, further motivating a comprehensive exploration of the remaining heavy WIMP parameter space.

Speaker: Maximilian Detering (King's College London)

155 Toward a real-time theory of vacuum decay

False vacuum decay plays a pivotal role in many models of particle physics and the early Universe, from inflation to the electroweak vacuum. However, we lack a satisfying theoretical understanding of this process, with existing approaches working only in imaginary (Euclidean) time, and relying on assumptions that have yet to be empirically tested.
In this talk, I will describe ongoing efforts to develop a real-time theory of vacuum decay by combining two new empirical approaches: semiclassical numerical simulations on the lattice, and quantum analogue experiments in the laboratory.

Speaker: Alex Jenkins (University of Cambridge)

156 Coffee Break

157 Search for the rare Higgs boson decay H -> Z gamma

We present a search for the rare Higgs boson decay H→Zγ using proton–proton collision data recorded by the CMS experiment at the LHC at center-of-mass energies of 13 and 13.6 TeV, corresponding to a total integrated luminosity of 200 fb⁻¹. The analysis targets final states where the Z boson decays to an electron or muon pair. Sensitivity is enhanced through dedicated event categorization optimized for different production modes. The signal is extracted from a simultaneous fit to the three-body (lepton pair and photon) invariant-mass distributions across all categories. For a Higgs boson mass of 125.38 GeV, the measured signal strength relative to the Standard Model expectation is μ = 1.10 (+0.52/-0.61), with an observed (expected) significance of 1.9 (2.3) standard deviations. These results provide an important test of loop-induced Higgs couplings and no significant evidence of physics beyond the Standard Model is observed.

Speaker: Xingchen Fan (Cornell University (US))

158 Searches for New Physics in Effective Field Theory Approaches from ATLAS

We present two analyses searching for new physics in the context of effective field theory approaches from the ATLAS collaboration. The analyses use multiple experimental measurements across a range of processes in electroweak boson, top-quark and Higgs production to constrain dimension-6 operators. In addition multi-boson production measurements provide leading constraints on anomalous quartic gauge couplings.

Speaker: Oleksii KURDYSH

159 Characterizing LHC-Resonances in extended HEFT

In theories with extended scalar sectors, the lightest new scalar could be accessible at colliders. Instead of relying on simplified models, we describe such scenarios in a general and gauge-invariant way using an extended HEFT framework with a nonlinearly realized electroweak symmetry. The structure of the effective operators depends on the $SU(2)$ nature of the scalar in the UV, leading to different suppressions by the heavy scale. In this talk, we show how dimensional analysis allows us to identify hierarchies among Wilson coefficients that translate into correlations between LHC observables, providing a model-independent strategy to interpret a potential scalar signal and infer its UV origin without fixing its $S U(2)$ representation.

Speaker: David Cabo Almeida (University of Göttingen)

160 Quantum Entanglement Is Quantum: Insights from Diboson Systems at the LHC

Polarisation and spin correlations in diboson systems are powerful probes for precision tests of the Standard Model and searches for new physics. More recently, viewing these observables through the lens of quantum information, such as assessing whether diboson systems exhibit quantum entanglement, has opened a compelling new frontier in these investigations. They also provide a unique opportunity to test quantum information principles at the highest accessible energy scales. We analyze the angular coefficients for the $pp \to ZZ \to 4 \ell$ and Higgs decay to di-bosons $h \to WW$ and $h \to WW$, incorporating higher-order QCD and electroweak corrections. For Higgs decays, we consider both fully leptonic and semileptonic final states. Guided by the fundamental properties of the spin density matrix, we assess the stability of the two-qutrit interpretation under radiative effects. For the $pp \to ZZ \to 4 \ell$ process, NLO QCD corrections preserve the two-qutrit structure but weaken entanglement indicators, an effect that can be partially mitigated by jet binning. In contrast, EW introduce non-factorizable contributions that modify the quantum properties of the system. While these effects can be largely depleted by selecting events with a double-resonant $ZZ$ structure, such a kinematic handle is not available for Higgs decays. For $h \to ZZ$, channel, singly-resonant NLO electroweak corrections substantially distort the angular coefficients, challenging the description of these events as a two-qutrit system. These effects are milder for $h \to WW$ compared with $h \to ZZ$. For both processes, semileptonic final states exhibit greater stability than fully leptonic final states.

Speaker: AJAY Kaladharan

Strings: String phenomenology/cosmology

Conveners: Ivonne Zavala, Susha Louise Parameswaran (University of Liverpool)

161 break

162 TBA

Speaker: Ivonne Zavala

163 TBA

Speaker: Prof. Lilia Anguelova (INRNE, Bulgarian Academy of Sciences)

164 Modular quintessence and de-Sitter in heterotic orbifolds

Recent results from DESI indicate that the accelerated expansion of the Universe may not be fully explained by a simple cosmological constant and instead may point toward a dynamical form of dark energy. At the same time, modular symmetries are emerging as important ingredients in string theory, as modular invariance is naturally built into many string compactifications. In this work, we explore a possible connection between these ideas by focusing on scalar potentials arising in heterotic orbifolds, where the underlying geometry simultaneously shapes the flavor structure and the dynamics of the moduli. An interesting feature is that the dynamics of these modular fields can give rise to multifield hilltop quintessence, compatible with recent observations and consistent with the Swampland conjectures.

Speaker: Hansel Gordillo Ruiz (UNAM, Mexico)

165 Coffee Break

166 Generalised anomalies, QCD, and holography

During the last decade, the notion of an 't Hooft anomaly has
been generalised to the case of discrete symmetries. An interesting
instance, discussed by Tanizaki, is the mixed anomaly between the
discrete axial symmetry and the flavour and baryonic symmetries in
massless QCD. The goal of this talk is to provide a derivation of this
anomaly from a top-down holographic dual of QCD. I will show that the
topological couplings in the bulk supergravity dual of the D4-D8 system
encode Tanizaki's anomaly, once fluctuations around the bulk gauge
fields are turned on. A technical challenge for this computation is the
difficulty in maintaining gauge invariance of supergravity theories in
the presence of D-branes. To overcome this issue, a compact formulation
of the flux sector of (massive) type IIA supergravity in the presence of
D8 branes is presented.

Speaker: Mohammad Akhond

167 SUSY and non-SUSY analysis of truly confining gauge theories

We classify 4D N=1 truly confining supersymmetric gauge theories, in which no center charges can be screened. This property guarantees that Wilson loops in the fundamental representation exhibit an area law. We systematically identify all such theories for simple Lie groups and determine the allowed matter content. In each theory, we find condensing magnetic operators, which are expected to explain confinement via the dual Meissner effect. We also analyze the non-SUSY versions of truly confining gauge theories and identify stable vacua that indicate confinement via the dual Meissner effect.

Speaker: Shota Saito (Kavli IPMU)

168 Brane-Cosmology

Holography(AdS/CFT correspondence) has proved to be quite useful in under-
standing field theory at the boundary from the information in the bulk and vice-
versa, the goal is to see if such a prescription can help us understand our universe

and provide a mapping between cosmology and a CFT defined on a manifold with

boundary(BCFT). The bulk geometry is taken to be AdS with an additional End-
Of-the-World (EOW) brane along with the asymptotic AdS boundary such that the

boundary in the dual BCFT theory corresponds to EOW brane on gravity. The ad-
vantage of this construction is that although the bulk geometry is taken to be AdS,

the space-time on the brane could be dS and thus could pave a way to study dS/CFT
by embedding in higher dimensional AdS/CFT.
First AdS3/BCFT2 is considered and matter fields (complex scalar) on the brane
are coupled to the gravitational dynamics of the AdS bulk, thus serving as potent
tools for cosmology. Then the analysis is extended to AdS5, to draw some conclusions
about our real world cosmology from branes with some big-bang like solutions.

Speaker: Lakshita Bageja (IISER,B)

169 TBA

Speaker: Susha Louise Parameswaran (University of Liverpool)

Lunch

Poster Award

Strings

170 TBA

Speaker: Salvatore Bottaro

171 Counting AdS Vacua

How many AdS vacua exist with no massive states below a given cutoff μ? Taking a bird's eye view over all string theory vacua, we find that most classes display a power-law growth as μ tends to zero. The exception comes from constructions that admit many brane charge choices, naively leading to an exponential growth. Taking into account moduli and tachyons suggests however a natural weight by the volume of field theory space, which damps the exponentials to power laws again. Vacua with a small number of light fields dominate in this measure.

Speaker: Alessandro Tomasiello

172 TBA

Speaker: Albrecht Klemm

Coffee Break

Cosmology

173 TBA

Speaker: Dr Djuna Croon (IPPP Durham)

174 Taylor expansion methods for loops during inflation and the decoupling of scales

Taylor expansion methods based on the separate universe approximation, or more general approaches that do not rely on this approximation, can provide insight into the debate on the strength of loop corrections in inflationary models with a large peak. Such a peak is needed for the production of primordial black holes and scalar-induced gravitational waves. In particular, these methods can clearly show how the peak scales decouple from predictions on CMB scales. These methods are also extremely useful for numerical simulations. After reviewing Taylor expansion methods, the codes that implement them, and the debate around loop corrections, I’ll highlight our recent results on the decoupling of scales.

Speaker: David Mulryne (Queen Mary University of London)