String Phenomenology 2025

7 Jul 2025, 01:30 → 11 Jul 2025, 19:00 US/Eastern

ISEC (Northeastern University)

The annual String Phenomenology conference discusses recent progress in compactifications of string theory and their relation to particle physics and cosmology.

Topics include:

• Swampland and Quantum Gravity Conjectures 
• Formal and Mathematical Aspects of string compactifications (such as F-theory, G2 compactifications, heterotic compactifications, and other corners of the string landscape, e.g. non-geometric compactifications)
• String Model Building in particle physics and cosmology
• Machine Learning Techniques to explore the String Landscape

Plenary Speakers:

Steven Abel	Severin Lüst
Lara Anderson	Liam McAllister
Joe Conlon	Jake McNamara
Mirjam Cvetič	Miguel Montero
Keith Dienes	Richard Nally
Markus Dierigl	Michael Nee
Michael Douglas	Georges Obied
Naomi Gendler	Paul Oehlmann
Thomas Grimm	Fernando Quevedo
Arthur Hebecker	Sav Sethi
Jonathan Heckman	Gary Shiu
Vishnu Jejjala	Eva Silverstein
Hee-Cheol Kim	Alessandro Tomasiello
Manki Kim	Irene Valenzuela
Johanna Knapp	Damian van de Heisteeg
Sven Krippendorf	Yinan Wang
Magdalena Larfors	Timo Weigand
Seung-Joo Lee	Alexander Westphal
Andre Lukas	Kazuya Yonekura
Dieter Lüst

 

Local Organizers:

• Rafael Álvarez-García
• Jim Halverson
• Thomas Harvey
• Fabian Ruehle
• Washington Taylor
• Cumrun Vafa

SP2025Poster.pdf

Monday 7 July

08:20 Registration

1 Welcome

2 The geometric II, III, IV of complex structure degenerations

Complex structure degenerations of Calabi-Yau threefolds at infinite distance have played an important role in testing various quantum gravity conjectures.
At the same time, their geometric properties are relatively less intuitive compared to their counterparts in Kähler moduli space. In particular, new geometric insights are needed to establish the existence of the leading towers of light states, including in particular those of asymptotically light critical strings in emergent string limits.
We will explain the geometric origin of these key quantum gravitational ingredients. At a technical level, the new input is a geometric interpretation of the three-cycles with asymptotically vanishing volume. Among other things, we will explain how Type IIB string theory on Calabi-Yau threefolds can be seen to be dual to heterotic string theory without invoking mirror symmetry, and develop new predictions for the counting of asymptotically vanishing three-cycles and for the types of complex structure limits that can be geometrically realized on Calabi-Yau threefolds.

Speaker: Timo Weigand

3 String Phenomenology and Gravitational Waves

An overview will be given about the importance of gravitational waves to search for future ways of comparing string theory to observations. In particular the spectrum of gravitational waves produced in the Hagedorn phase will be highlighted as well as the recent progress on the search for high frequency gravitational waves.

Speaker: Fernando Quevedo

4 Complexity bounds in the String Landscape

Speaker: Thomas Grimm

10:30 Coffee Break

5 Quantum tunneling in the geometric landscape

Speaker: Yinan Wang

6 Quantum stress-energy at timelike boundaries: testing a new beyond-ΛCDM parameter with cosmological data

We analyze the basic cosmological effects of a population of timelike boundaries – a form of nontrivial
spacetime topology – containing a boundary layer of quantum stress energy. This accumulation of
vacuum fluctuations of quantum fields can be consistently negative and UV sensitive, providing an
additional source of cosmic energy density strong enough to compete with matter and dark energy.
For boundary conditions enabling a solution with fixed comoving boundary size, this effect contributes
a qualitatively new term to the Friedmann equation determining the expansion history, scaling like
−1/a for scale factor a. It naturally dominates at relatively late times (a ≈ 1/2), while leaving intact
well-measured early universe physics such as big bang nucleosynthesis and recombination. For a wide
window of parameters, the boundaries can be larger than the Planck length throughout their history,
back through the start of inflation at any viable scale. We analyze CMB and BAO data sets (Planck,
ACT, and DESI) allowing for this component, finding a slight preference (∼ 2σ) and a relaxation of
current tensions in the data (including the neutrino mass) in a physical manner. This novel parameter
fits into a larger space of physical parameters beyond-ΛCDM that may serve this role, including
negative spatial curvature, which may also be motivated by topological considerations and chaotic
dynamics. Finally, we comment on additional phenomenological prospects for testing for this form of
topology in the universe.

Speaker: Eva Silverstein

12:00 Lunch

7 Building the Axiverse

Speaker: Liam McAllister

8 Axion Couplings in Heterotic String Theory

Speaker: Michael Nee

9 QCD Axion Dark Matter and Hierarchies in the Axiverse

Speaker: Naomi Gendler

15:00 Coffee Break

10 ¡The R7-Brane is Stable!

The Swampland Cobordism Conjecture predicts the existence of several novel non-supersymmetric objects. These include the existence of a domain wall between IIA and IIB string theories, as well as R7-branes in F-theory in which the F-theory torus undergoes a reflection in winding around the R7-brane. In this talk we argue that the long string probe characterization of the IIA/IIB wall is an interface between different GSO projections. Moreover, wrapping this GSO wall on a bubble-like configuration with IIB on the outside leads to a collapsing configuration with stable endpoint an R7-brane; a GSO vortex. We also sketch some potential applications in string compactification and model building. Based on joint work with McNamara, Parra-Martinez, and Torres.

Speaker: Jonathan Heckman

11 Symmetries and M-theory-like Vacua in Four Dimensions

Non-geometric flux vacua have recently been revisited, leading to the remarkable discovery of isolated 4D N=1N=1 supersymmetric Minkowski vacua. These constructions rely on the non-renormalization of the superpotential, which is supported by heuristic arguments. Given the significance of verifying the existence of these isolated M-theory-like vacua, we present alternative symmetry-based arguments that arrive at the same conclusion. Additionally, we leverage these symmetries to argue for the existence of unstable dS solutions as well as supersymmetric AdS solutions.

Speaker: Damian van de Heisteeg

12 Building a Calabi-Yau Factory

Speaker: Gary Shiu

13 Stasis, Stasis, Stasis: The Universe on Pause

Speaker: Keith Dienes

18:00 Reception

Tuesday 8 July

08:30 Registration

14 Precision String Phenomenology

Calabi-Yau compactifications of string theory lead to quantum field theories in four dimensions with chiral matter. Calculating parameters of the low-energy effective theory in general compactifications requires the Ricci-flat metric on the Calabi-Yau manifold. Such metrics are not known analytically. In this talk, we discuss how to approximate the Ricci-flat metric using neural networks. The accuracy of the numerical metrics is assessed for K3 and the quintic threefold. In the standard embedding, we calculate Yukawa couplings for compactifications on various Calabi-Yau geometries and show the existence of hierarchies. This is an initial step toward a first principles calculation of particle masses from string theory.

Speaker: Vishnu Jejjala

15 Classical and quantum aspects of N=1 heterotic G2 compactifications

Supersymmetric flux compactifications of string theory are coupled system of gauge theory and gravity. In all such systems, the interplay between gauge fields, flux and geometry makes it non-trivial to determine the deformation theory that governs the compactification moduli. In this talk, we explore this question in N=1 compactifications of the heterotic string on 7D G2 structure manifolds. We will present a classical deformation theory for these systems, that rely on an elliptic double complex, that we will explicitly construct. This will allow us to compute infinitesimal moduli and their obstructions. Our analysis is governed by a real superpotential, which we determine by dimensional reduction. Finally, we will outline the computation of the one-loop partition function of the heterotic G2 system, and how it decomposes into a product of one-loop partition functions of Abelian and non-Abelian instanton gauge theories.

Speaker: Magdalena Larfors

16 AI for the String Landscape: Targeted Discovery in Type IIB Flux Vacua

Understanding the vast landscape of string theory vacua is a central challenge in connecting fundamental theory to low-energy phenomenology. In this talk, I present recent advances in using machine learning — specifically conditional generative models — as tools for automated discovery in the string landscape. Focusing on the inverse problem in Type IIB flux compactifications, I demonstrate how Conditional Variational Autoencoders (CVAEs) can efficiently generate flux vacua with targeted properties, such as specified values of the superpotential or satisfying strict tadpole constraints. These models enable controllable sampling in regions of moduli space that are computationally inaccessible via traditional methods like MCMC, achieving speedups of several orders of magnitude while discovering physically novel vacua beyond the training data.

Complementing this, I will also present a framework for systematic enumeration of flux vacua in compact regions of moduli space using a tailored algorithm, applied to a two-modulus Calabi-Yau orientifold. This analysis reveals detailed structure in the vacuum distribution, including hierarchical mass scales and rare vacua with very small superpotentials, offering a complementary, data-driven view of the landscape.

Together, these results illustrate how AI methods can augment theoretical tools to enable both exploratory and targeted investigation of the string landscape — with potential implications for bottom-up model building and upcoming agent-based scientific discovery.

Speaker: Sven Krippendorf

10:30 Coffee Break

17 Invariants of 2d N=(0,1) supersymmetric field theories

Two-dimensional N=(0,1) supersymmetric field theories have subtle invariants beyond the standard elliptic genus. They have applications to heterotic strings and cobordism conjecture. In the talk, I will discuss these invariants.

Speaker: Kazuya Yonekura

18 Non-linear sigma model in string field theory

I will describe how to construct data of the worldsheet CFT of the strings probing a curved background with a non-trivial topology in string field theory. As a simple application, I will describe how to use this result to compute the D-instanton superpotential and loop corrections to the Kahler potential in Calabi-Yau orientifold compactifications in the large volume limit. This talk is based on my upcoming work.

Speaker: Manki Kim

12:00 Lunch

Parallel Session 1

19 The Gravitational Double EFT Expansion

In this talk, we will explore the structure of EFTs within the context of Quantum Gravity, using string theory as a laboratory. Using an amplitudes-based approach, we argue that any EFT describing Quantum Gravity should exhibit a double expansion for higher-curvature operators, which includes terms supressed with respect to the Einstein-Hilbert term by either the mass of the lightest tower of states or by the Quantum Gravity cutoff, which we identify as the species scale. We furthermore characterize the kind of breaking of the gravitational EFTs associated to each of these two scales. Then, we will briefly discuss some implications of this framework for the asymptotic behaviour of Wilson coefficients of higher-dimensional gravitational operators, revealing interesting connections with recent S-matrix bootstrap results.

Speaker: Alvaro Herraez

20 Probing UV scales with Classical Black Holes

I will outline how large classical BPS black hole solutions which feature an attractor mechanism can be used to probe large distances in moduli space at the horizon. I will show how these classical 2-derivative solutions seem to know about UV scales such as the species scale and the KK scale, in contrast with standard ``EFT'' reasoning. I will then explain that this is possible only because of the lack of cosmological moduli stabilisation. I will with comments on the implications of this for black holes in our universe and the fuzzball proposal.

Speaker: Matilda Delgado

21 End of the World Branes and Chiral Theories

Chirality provides a powerful topological tool to study the cobordism conjecture, which states that any theory of quantum gravity should admit end of the world (ETW) boundaries of spacetime. I discuss two realizations of this idea: First, I consider explicit 6d and 4d string theory models realizing gravity theories with chiral matter content, and construct explicit ETW boundaries which gap the chiral non-anomalous sector via strong coupling phenomena, such as strongly coupled phase transitions or symmetric mass generation. Second, I consider a class of 5d gravity theories (closely related to holographic AdS_5 x S^5 setups) with 4d ETW branes supporting chiral anomalous fermions. The boundaries are AdS_4 Karch-Randall branes, supporting localized gravity, and leading to a seemingly anomalous (hence inconsistent) 4d gravity theory theory, which is happily saved by an anomaly inflow from the 5d bulk. This motivates the concept of Relative Quantum Gravity Theory, which posits that a D-dimensional gravity theories may seem to violate familiar quantum gravity and swampland constraints, but attain a consistent completion when coupled to a (D+1)-dimensional theory.

Speaker: Chuying Wang

22 SL(2,Z), commutators and bordisms between 9d type IIB supergravities

Using type IIB 9d gauged supergravities as an example, I will discuss how non-trivial topology plays a crucial role in bordisms to nothing or to other gauged supergravities, by allowing monodromies along its 1-cycles, which reduces the number of bordism defects that naively one would have needed. I will then explain how a property of the duality group, in this case SL(2,Z), known as commutator width, restricts the general viability of this approach, in such a way that additional defects must be considered or the duality bundle enlarged.

Speaker: Ignacio Ruiz

23 EFT strings and dualities: a bottom-up perspective

The bottom-up origin of the Swampland Distance Conjecture (SDC) and its relation to string dualities remains an open puzzle. In 4d 𝑁 = 1 N=1 theories, the existence of ½-BPS EFT string solutions provides a bottom-up realization of these infinite distance limits. In this presentation, I will explore an intriguing integer scaling relation between EFT strings becoming asymptotically tensionless, the light towers of the SDC, and the emergence of perturbative duality frames. I will show that this scaling implies a unique arrangement of light towers along different moduli space directions, determined solely by the 4d EFT data—without requiring knowledge of the precise string embedding. Remarkably, these predictions coincide with known string constructions, hinting at yet another instance of string universality. This key observation allows us to reverse the logic and formulate a set of bottom-up criteria that predict how SDC towers are distributed in moduli space. I will conclude by discussing how these results can be used to constrain candidate Kähler potentials in 4d effective theories.

Speaker: Alessandra Grieco

Parallel Session 2

24 No Need To Be Vexed: CY Hypersurfaces from Reflexive Polytopes Beyond FRSTs

The Krezuer-Skarke (KS) database of toric hypersurface Calabi-Yau (CY) threefolds arising from fine, regular, star triangulations (FRSTs) of 4D reflexive polytopes—following Batyrev's original construction—has long provided an important setting for explicit model building in string phenomenology. It is known, however, that the Kahler moduli spaces of KS Calabi-Yau geometries are not fully described by FRSTs: rather, they can contain geometries that do not admit an obvious Batyrevian hypersurface description; these are more difficult to study, and are thus not well understood. Such geometries have been discussed in the literature using monikers such as "non-toric phases" or "vex triangulations." In this talk, we explain how the secondary fan can be used to organize all toric fans associated to a reflexive polytope. In the process, we will clarify the differences between FRSTs and vex triangulations, and we will illustrate — through concrete examples and exhaustive enumeration at small Hodge numbers — how the latter category can be employed in practice to describe a much larger subset of KS CY Kahler moduli spaces using toric geometry. Hopefully, the presented methods and examples will help enable the systematic employment of non-FRST toric fans in string phenomenology.

Speaker: Elijah Sheridan

25 No Shift, Sherlock

In this talk, I will present a novel CFT-based argument against continuous shift symmetries in AdS/CFT. Unlike other global symmetries, continuous scalar shift symmetries have a clear CFT counterpart: the existence of a conformal manifold along which the CFT data does not change. This allows us to ask whether a local and unitary CFT can exhibit such a property. We provide a purely CFT argument against this possibility. To clarify the role of locality on the CFT (or equivalently, having quantum gravity in the bulk), we also describe how this property is realized in the dual theory of a massless free scalar in rigid AdS, namely the generalized free field theory of a marginal operator. Crucially, this realization of the shift symmetry relies on the boundary theory being non-local.

Speaker: José Calderón-Infante

26 Kernel Bundles with Real and Symplectic Structure

The monad bundle construction is a useful tool to build a large class of holomorphic, polystable vector bundles for use in heterotic string compactifications. While it is well-known how to construct monad bundles with SU(n) structure, constructing monad bundles with reduced structure groups remains relatively unexplored. In this talk, we will introduce new techniques to construct kernel bundles with SO(n) and Sp(n) structure groups, and provide examples of how this can be used to realize Higgsing transitions in the heterotic setting. We will also comment on how this approach could be extended to construct vector bundles with exceptional structure groups.

Speaker: Andrew Turner

27 Fermionic Gauge Symmetry in Target Space Duality

TBA

Speaker: Sunit Patil

28 Computation of the index on orbifold

We investigate the independent chiral zero modes on the orbifolds from the Atiyah-Segal- Singer fixed point theorem. The required information for this calculation includes the fixed points of the orbifold and the manner in which the spatial symmetries act on these points, unlike previous studies that necessitated the calculation of zero modes. Since the fixed point theorem can be applied to any fermionic theory on any orbifold, it allows us to determine the index even on orbifolds where the calculation of zero modes is challenging or in the presence of non-trivial gauge configurations.

Speaker: Maki Takeuchi

Parallel Session 3

29 Flavor Symmetries and Winding Modes

Modular flavor symmetries have been proposed as a new way to address the flavor problem. It is known that they can emerge from string compactifications. We discuss this connection in detail, and show how the congruence subgroups of SL(2,Z), which underlie many modular flavor symmetries, emerge from stringy duality symmetries by orbifolding. This requires an analysis of massive states, which reveals a picture that is more intricate than the well-known situation on the torus. It involves towers of states of different quantum numbers, related by modular transformations. Members of different towers become massless at different points in moduli space. We also show that, at least in the Z3 orbifold, the string selection rules can be understood as discrete remnants of continuous gauge symmetries. Non-Abelian discrete flavor symmetries arise as discrete remnants of various, relatively misaligned, continuous Abelian gauge symmetries. The generators of these U(1)symmetries give rise to CP-violating Clebsch–Gordan coefficients. If the modulus settles close to a critical point, the corresponding gauge bosons may be light enough to be searched for at future colliders.

Speaker: Alexander Stewart

30 Cosmological trackers from perturbations

Compared to standard cosmology, string cosmologies motivate an extended period of kination that can be followed by a cosmological tracker and then an epoch of moduli domination. Conventionally, such trackers occur when there is a scalar field with an exponential potential and an additional fluid whose energy balances the kinetic and potential energy of the scalar field. In this talk we show that a tracker can also be reached even when the universe only contains a scalar field, with no additional fluid. In this case perturbations in the scalar field can effectively behave like a radiation fluid, leading to a radiation tracker at late times.

Speaker: Martin Mosny

31 F-theory Axiverse

TBD

Speaker: Yunhao Zhu

32 Axion masses, decay constants, and photon couplings in F-theory ensembles

We compactify F-theory on Weierstrass models over various toric threefold bases, and compute the masses, decay constants, and photon couplings of the associated axions.

Speaker: Sebastian Vander Ploeg Fallon

33 Unstable Domain Walls and Transitions in the Flux Landscape

Domain walls which arise from the presence of a brane coupled to a modulus field is the setting relevant for studying flux-changing D5/NS5-branes in the type IIB flux Landscape which couple to the volume modulus. In this talk I will revisit known results on the subject and explain that if the modulus is only weakly stabilized, as is the case for scenarios à la KKLT or LVS, no Euclidean tunneling instanton can be found due to the too strong backreaction of the brane. As a result, the transitions populating such a de Sitter Landscape cannot be of standard Coleman–de Luccia type. Solving the cosmological constant problem in the usual dynamical way by populating a multiverse then either requires better scenarios or a deeper understanding of transitions of non-tunneling type. Back to a Lorentzian picture, this leads us to sketch a framework to describe a new type of dynamical transition that may rescue the population of the Landscape.

Speaker: Thibaut Coudarchet

15:00 Coffee Break

Parallel Session 1

34 Fractionally Confined Monopoles in Failures of the Lattice Weak Gravity Conjecture

The Weak Gravity Conjecture and its various refinements form a cornerstone of the swampland program. While many examples satisfy the Lattice Weak Gravity Conjecture (LWGC), where a superextremal state is present at every site of the charge lattice, there are exceptional examples where only a (finite index) sublattice of superextremal states are present. Following my recent work 2502.14951, we examine the common features of these LWGC violating theories. In particular, we find that associated to the sublattice of superextremal states there is a dual superlattice of confined monopoles. Moreover, as the violation becomes more extreme the tension of the confining flux tubes becomes light. After introducing the mechanics of this relation I will discuss EFTs where these confined monopoles enter, and landscape examples of these EFTs (where we can make precise relations between the violation and the flux tube tension).

Speaker: Sebastian Rauch

35 The Gravitino and the extra dimensions

We investigate the relation between the existence of extra dimensions and the scale at which supersymmetry is expected to break down, linking it to the threshold at which the Effective Field Theory description becomes invalid. We use the Gravitino Conjecture(GC) to make predictions on the number and the size of extra dimensions based on the value of the gravitino mass, ensuring our results align with most recent constraints on extra dimensions. For doing so, we generalize the GC by introducing a dependence on the number of mesoscopic extra dimensions considered in supergravity theory, using results of string compactification. We draw scenarios connecting the values of the gravitino mass and of the scale of supersymmetry break down to the phenomenology of the extra dimensions. In detail, we explore the experimentally viable case where the size of the extra dimensions is comparable to the distance at which deviations from Newtonian gravity have not yet been detected. Finally, we draw scenarios also where the mass of the gravitino is enough high for allowing to gravity mediation for the breaking of supersymmetry.

Speaker: Leonardo Bersigotti

36 The Horizon Criterion for Spacetimes with boundaries

It has been speculated that de Sitter space is problematic in quantum gravity due to the presence of cosmological horizons. By considering spacetimes with dynamical boundaries, we argue that if a swampland criterion related to horizons can be formulated, it has to go beyond simply demanding the absence of cosmological horizons. We formulate an appropriate condition and analyze its consequences for situations where the boundary energy-density is set by a scalar field.

Speaker: Bjoern Friedrich

37 Navigating String Theory Field Space with Geometric Flows

"A notion of distance on the moduli space of low-energy effective field theories is crucial for the Swampland program, and specifically for the Distance Conjecture. In this talk, I will show how geometric flow equations, and in particular generalizations of the Ricci flow, offer a different and elegant viewpoint in the more general case of a scalar field space with potential. After a brief introduction to Ricci flow and its generalization to backgrounds involving a NSNS two-form, I will review the known realization as a gradient flow of the string-effective action and the associated beta-functions, ultimately proposing a suitable notion of distance along the flow as well as a generalized Ricci flow Conjecture. I will discuss examples highlighting the new and intriguing implications as well as the connection to previous work on the role of (diverging) potentials.
This work is in collaboration with Saskia Demulder and Dieter Lüst."

Speaker: Thomas Raml

38 Quantum Corrections and Distance Conjecture in Asymmetric Orbifolds

TBD

Speaker: Guoen Nian

Parallel Session 2

39 Black Hole Entropy, Quantum Corrections and EFT Transitions

We revisit and study quantum corrections to the supersymmetric entropy of BPS black holes in 4d N = 2, which can be obtained from Type IIA string theory compactified on a Calabi-Yau threefold. Macroscopically, these corrections arise from an infinite series of higher-derivative F-terms that encode certain modifications to the two-derivative supergravity effective action. Within the large volume regime we show that the entropy captures, in a rather intricate way, the transition between four- and five-dimensional dual EFT descriptions. In fact, the expansion parameter controlling the relevant asymptotic series can be related to the ratio of the black hole horizon and the Kaluza-Klein scale, given here by the inverse D0-brane mass. Furthermore, we are able to resum the series into a well-behaved convergent expression for all values of the parameter. This demonstrates, in turn, that (stable) black holes can, indeed, probe scales besides the quantum gravity cutoff. We are able to study the most general BH configuration with D0-D2-D4-D6 charges. We find that despite being stable, this configuration can receive non-perturbative corrections due to virtual particles pair production. We characterize this quantum effects giving a both a semi-classically description and a precise 1-loop evaluation.

Speaker: Matteo Zatti

40 On Quantum Corrections to Black Hole Entropy

We investigate quantum corrections to the supersymmetric entropy of BPS black holes in 4d N=2 effective field theories, derived from Type IIA string theory on a Calabi–Yau threefold. These corrections arise from an infinite series of higher-derivative F-terms modifying the two-derivative supergravity action. Within the large volume regime, we analyze their moduli dependence as well as the implications for black hole entropy. Our results reveal a clear-cut connection between the perturbative entropy expansion parameter and the ratio of the black hole horizon to the (dual) M-theory Kaluza-Klein scale, allowing us to resum the series into a well-defined expression valid beyond the latter energy cutoff. By closely examining the D0-D2-D4 and D2-D6 BPS systems, we show how perturbative quantum effects resolve the apparent UV divergences, leading to a consistent entropy function for all values of the expansion parameter. Moreover, in certain cases, we recover the exact microstate counting of the corresponding five-dimensional black string via circle decompactification. Notably, non-perturbative corrections do not alter our conclusions, further supporting the robustness of our findings.

Speaker: Alberto Castellano Mora

41 Higher-Dimensional Fermionic SYK Model in IR Region

We study the 2D fermionic SYK model with Majorana fermions, featuring a kinetic term with a quartic expression and a $2q$-body interaction with Gaussian disorder. By minimizing the effective action or solving the SD equation for $q=1$, we determine that the appropriate ansatz involves zero spins. Our computation of the Lyapunov exponent shows violations of chaos and unitarity bounds. The gravitational dual corresponds to AdS$_3$ Einstein gravity with a finite radial cut-off even if we lose the non-zero spins. We also extend the SYK model to higher dimensions while maintaining a similar SD equation in the IR.

Speaker: Chen-Te Ma

42 Vanishing Terms in Heterotic Effective Theories

TBA

Speaker: James Gray

43 Non-geometric compactifications from Landau-Ginzburg models

One of the challenges of Calabi-Yau compactifications is to stabilise the complex structure and Kähler moduli corresponding to the deformations of the internal space. If they were left massless, they would give rise to phenomenologically irrelevant string vacua. In type IIB string theory, only complex structure moduli can be stabilised by turning on fluxes in the internal space. Besides, the tadpole conjecture proposes that the number of stabilised moduli has to grow linearly with the tadpole charge of the fluxes. We study models of compactification constructed from Landau-Ginzburg worldsheet theories, which allow for non-geometric compactifications on Calabi-Yau spaces with no Kähler moduli. These models could in principle explicit vacua with all moduli stabilised by fluxes. We will review the ingredients of flux compactification of the 2^6 LG model and examine the tadpole conjecture in this framework.

Speaker: Miguel Morros

Parallel Session 3

44 Alignment and Co-Scaling of Electric and Magnetic Towers

In regions of the landscape with a tower of light electrically charged particles or branes -- those with charge-to-mass (or tension) ratio parametrically larger than 1 in Planck units -- one also finds a tower of light magnetically charged particles or branes with the same charge-to-mass ratio. We call this phenomenon "electric-magnetic co-scaling." These towers are, furthermore, aligned; their charge-to-mass ratio vectors point in the same direction, as measured by the kinetic terms of the gauge fields. I will discuss examples and heuristic reasons for this to be true, and comment on phenomenological applications, including an upper bound on the quantum gravity cutoff in theories of extra-dimensional axions. (Based on 2406.08543 and work in progress with Tom Rudelius and Christopher Tudball.)

Speaker: Matthew Reece

45 Learning New Constructions of Toric Calabi-Yau Manifolds with Transformers

Fine, regular, and star triangulations (FRSTs) of 4-dimensional reflexive polytopes generate toric varieties, within which Calabi-Yau threefolds can be embedded as hypersurfaces. We use transformers---deep learning models originally developed for language modeling---to generate FRSTs of polytopes of varying sizes. Our method shows promising scalability with polytope size and can be continuously improved through self-improvement and priming strategies, laying the groundwork for a self-updating online database of Calabi-Yau manifolds.

Speaker: Jacky Hoi Tung Yip

46 Cosmic superstrings in large volume compactifications: PTAs, LISA and time-varying tension

The Stochastic Gravitational Wave Background (SGWB) from cosmic super- strings offers one of the few known possibilities to test String Theory within current experimental reach. However, in order to be compatible with the existing constraints, the tension of a cosmic superstring network is required to lie several orders of magnitude below the Planck scale. This is naturally realized in string compactifications where the volume of the extra dimensions is parametrically large (in string units). We estimate the GW spectrum arising from cosmic superstrings in such scenarios, providing analytical formulae as well as numerical results and a comparison to observation. Crucially, we do so within a fully-fledged string cosmology, taking into account various modified cosmological epochs (such as kination or early matter domination) induced by the presence of moduli and a time-dependent string tension.

Speaker: Filippo Revello

47 Astrophysical aspects of string compactifications

A generic aspect of effective field theories coming from string compactifications is the appearance of moduli fields. Among these moduli, the axion and dilaton are present at low energies as (pseudo-)Goldstone bosons from the spontaneous breaking of an exact (or approximate) global symmetry. These moduli have a different microscopic coupling to matter but appear kinetically coupled in such a way that their interaction can compete with gravity at low energies and have an important effect in strong gravity environments. In this talk, we will discuss some of the astrophysical implications of a stringy-inspired multi-scalar-tensor theory. In particular, we show numerically the existence of a screening mechanism that reduces the Brans-Dicke dilaton coupling to macroscopic matter sources such as a neutron star.

Speaker: Mario Ramos Hamud

48 A Dynamical Axion Decay Constant with Modulus Kination

We consider a QCD axion coming from the compactification of extra dimensional gauge fields. In this scenario, the QCD axion is around during inflation and seeds isocurvature. In the standard cosmic picture where reheating immediately follows inflation, CMB isocurvature bounds imply a low inflationary energy scale if the QCD axion were to comprise all of the dark matter. This poses an obstacle, known as the axion isocurvature problem, since it is difficult to construct low-scale inflation scenarios that are consistent with our observations of the CMB. We tackle this problem by considering an additional epoch between inflation and reheating: bulk-modulus kination. During this epoch, the axion decay constant is dynamical and decreases with time. In particular, we are interested in determining whether a large initial decay constant that supports high-energy inflation can decrease fast enough during bulk-modulus kination such that its final value is small enough to be consistent with CMB bounds. Towards this end, we investigate how the particle production of axions coupled to the modulus field can halt kination in order to determine the duration of this epoch and the associated change in the QCD axion decay constant.

Speaker: Chandrika Chandrashekar

Wednesday 9 July

08:30 Registration

49 Echo-Sounding Axiverses

The axiverse comes in different varieties (‘axiverses’) depending on their origin. Taking a closer look at the heterotic axiverse, we find the instanton-induced axion mass spectrum, as well as their matter sector couplings to be quite different from type IIB. We then look how leftover axiverse ‘echoes’ such as the presence of fuzzy DM, high-frequency GW production from axion inflation, or a dark radiation signal from axionic preheating, can be used toward ‘sounding’ out the type of axiverse.

Speaker: Alexander Westphal

50 Cosmic Superstrings in the Early Universe

Very few constraints exist on the universe between inflation and Big Bang Nucleosynthesis. String cosmology motivates non-standard behaviour in this epoch, in particular extended kination and tracker epochs associated to rolling moduli. Particularly interesting is the behaviour of cosmic (super)strings in such epoch: small loops of cosmic string can grow, and there exists an attractor solution in which three-quarter of the energy density of the universe lies in fundamental strings. Work based on 2401.04064, 2406.12637 and 2505.14187.

Speaker: Joe Conlon

51 End-of-the-World Branes and the Beginning of the Universe

I will start by explaining in which precise sense the Measure Problem remains important even though our picture of the Landscape may have changed. I will then argue for a fundamental, quantum mechanical approach, which suggests that conditions on the initial state of the universe are, in fact, decisive. Thus, arguably, Cosmological Initial Condition Problem is a more fitting term. I will discuss the Hartle-Hawking and Linde-Vilenkin proposals explaining that there are good reasons to take the latter seriously. This implies that End-of-the-World branes are absolutely crucial for inflationary and other predictions, leading to well-defined challenges for future research.

Speaker: Arthur Hebecker

10:30 Coffee Break

52 Computing Yukawa couplings from string theory

I will discuss how to compute Yukawa couplings in realistic heterotic string models, using machine learning techniques. More specifically, I will explain how training of neural networks can be used to find the main geometrical ingredients of string theory Yukawa couplings, namely approximate Ricci-flat metrics on Calabi-Yau manifolds, Hermitian Yang-Mill connections and harmonic bundle-valued forms. The techniques are illustrated for a specific string model with a low-energy standard model spectrum.

Speaker: Andre Lukas

53 How will we use AI in theoretical physics?

TBA

Speaker: Michael Douglas

12:00 Free afternoon

Thursday 10 July

08:30 Registration

54 Dark dimension boundary or shiny bulk? - Modular Quintessence

The latest DESI DR2 results, when combined with other independent cosmological data on the Cosmic Microwave Background and supernovas, suggest a preference for dynamical dark energy.
I the talk a will present a cosmological scenario, which features two distinct scalar fields.
One governs the magnitude of the present-day dark energy density and is related to the size of extra-dimensions. Accounting for the observed smallness of this energy density requires the scalar to reside near the boundary of field space.
The second field, responsible for the time evolution of dark energy and associated with the string coupling, must instead lie in the bulk to remain consistent with the non-observation of light string states. We show that a natural candidate for such dark energy dynamics is a quintessence modular-invariant potential, in which the second scalar field rolls down a negatively curved slope, starting from a self-dual critical point. We find that this scenario is in good agreement with the latest findings by DESI.

Speaker: Dieter Lüst

55 Mapping Moduli Spaces Across Geometric Transitions

I will highlight recent progress in studying new (potential) dualities in 4-dimensional N=1 theories and how moduli spaces in heterotic theories can extend across multiple background geometries connected by geometric transitions.

Speaker: Lara Anderson

56 Riemann-flat manifolds + Casimir energies + flux = dS maximum in M-theory

TBD

Speaker: Miguel Montero

10:30 Coffee Break

57 Exploring U-topia

In this talk we will explore different topological charges of supergravity theories supported by a non-trivial U-duality bundle. In case these charges would be conserved, they would lead to global symmetries, which we believe to be absent in any consistent theory of quantum gravity. With the UV completions of string and M-theory at hand, we explore which kind of UV objects are necessary to break all global symmetries in the IR supergravity theory. This leads to interesting string backgrounds including higher-dimensional superconformal field theories, twisted compactifications, and non-geometric defects.

Speaker: Markus Dierigl

58 Anomaly Coefficients and Eta Invariants for Quantum Field Theories in Geometric Engineering

In recent years, much progress has been made in understanding the extra-dimensional origin of higher symmetry structures of many quantum field theories (QFTs) obtained via geometric engineering. Among others, our understanding of anomaly structures in QFTs has been significantly improved. Key in these considerations is the asymptotic boundary of the internal dimensions which geometrizes many topological QFT features. Within this context we present explicit results for anomaly coefficients in 5D supersymmetric QFTs that are engineered in M-theory on Calabi-Yau three-folds, and show that eta-invariants of the asymptotic boundary of the engineered geometry determine 1-form self-anomaly coefficients. For isolated orbifold singularities this leads to closed form expressions which in toric cases are checked against intersection computations of resolved geometry. For non-isolated singularities these contributions receive corrections which we make explicit in families of examples.

Speaker: Mirjam Cvetič

12:00 Lunch

Parallel Session 1

59 Emergence of F^4-couplings in Heterotic/Type IIA theories

The M-theoretic emergence proposal claims that in an isotropic decompactification limit to M-theory the full effective action is generated via quantum effects by integrating out only the light towers of states of the theory. In the BPS particle sector, these include transversally wrapped M2- and M5-branes possibly carrying Kaluza-Klein momentum. A longitudinally wrapped M5-brane, i.e. a wrapped D4-brane, is thus not included in emergence computations. In this talk, we collect explicit evidence supporting this point via an F^4 gauge coupling in six dimensions, using the duality between heterotic string theory on T^4 and strongly coupled type IIA on K3. The goal is not only to test the M-theoretic refinement of the Emergence Proposal but also to interpret it as a tool to make predictions for the microscopic behavior of string amplitudes.

Speaker: Antonia Paraskevopoulou

60 Gravity Decoupling Limits & Moduli Space Invariants

TBD

Speaker: Lorenzo Paoloni

61 Non-susy moduli self-fixing

In 4D supersymmetric quantum gravity, moduli-dependent species scales imply a field-dependent cutoff. We show that in GKP-like no-scale vacua, this leads to one-loop, positive-definite potentials with Minkowski minima at “desert points” ($z_i \sim \mathcal{O}(1)$). The potential exhibits a dS maximum and asymptotic runaway, aligning with Swampland constraints. This mechanism may stabilize Kähler moduli without relying on non-perturbative effects. We illustrate it in a Type IIB $Z_2 \times Z_2$ orientifold, where modular invariance helps control corrections, and comment on its phenomenological embedding into intersecting D6-brane MSSM-like models.

Speaker: Gonzalo F. Casas

62 Formulating the Weak Gravity Conjecture in AdS Space

We recently proposed a version of the Weak Gravity Conjecture that applies to AdS spacetime. We find that the condition on the charge-to-mass ratio of a charged particle in AdS spacetime is corrected compared to the one in Minkowski spacetime by contributions that depends on the AdS scale and the horizon radius of the extremal Reissner–Nordström black hole charged under the same gauge theory. We motivate our proposal from the viewpoint of extremal black hole decay and show that the bound on the particle spectrum is given by the critical charge-to-mass ratio beyond which the Schwinger effect can take place. This quantum effect shares the same condition as requiring a particle to satisfy a repulsive force condition at the black hole horizon, so that the extremal black hole can decay without reabsorbing the particle. We also comment on the generalization in the case of multiple U(1) gauge theories, providing evidence for a convex hull condition in AdS background.

Speaker: Alessandro Mininno

63 Taxonomy of branes in infinite distance limits

I consider flat slices of moduli space where (−∇logT)-vectors of particle-towers and branes are constant, and I show that the Emergent String Conjecture constrains these vectors to reside on lattices. I further identify conditions that determine whether a given lattice site must be populated, and I show that only a finite set of configurations satisfies these conditions. I classify all such configurations for 0d, 1d, and 2d moduli spaces in theories with 3 to 11 spacetime dimensions, and I argue that 11d is the maximal spacetime dimension compatible with my assumptions. Remarkably, this classification reproduces the detailed particle and brane content of various string theory examples with 32, 16, and 8 supercharges. It also describes some examples where the assumptions I use are violated, suggesting that my assumptions can be relaxed and the scope of this classification can be expanded. It might also predict new branes. For instance, if heterotic string theory is described by this classification, then it must possess non-BPS branes with D-brane-like tensions. Similarly, if this classification applies to the Dark Dimension Scenario with an extra modulus, then it requires strings with a mass scale at or below the twelfth root of the cosmological constant in 4d Planck units. Based on 2505.10615.

Speaker: Muldrow Etheredge

Parallel Session 2

64 $G_2$-manifolds from Diophantine equations

I will argue that perturbatively flat vacua of type IIB string theory are dual to M-theory compactifications on $G_2$-manifolds without four-form flux. As a consequence, one can, implicitly, construct enormous numbers of $G_2$-manifolds by solving Diophantine equations in type IIB flux quanta. This duality can be used to compute warping corrections to the Kähler potential and Kähler coordinates on the type IIB side via a purely geometric computation on the M-theory side, and I will argue that such a computation may plausibly be necessary in order to control type IIB flux compactifications stabilized by instantons.

Speaker: Jakob Moritz

65 (-1)-form symmetries and SymTFT

TBA

Speaker: Subham Roy

66 Decoding IR Dualities and Phases with Quad-CFTs in N=1 SU(N) Gauge Theories

In this talk, I will discuss ​about our work on understanding the infrared (IR) dynamics of four-dimensional N=1 SU(N) chiral gauge theories with antisymmetric or symmetric rank-2 tensor matter. While Seiberg duality has been instrumental in constructing dual descriptions for theories with fundamental and anti-fundamental matter a systematic duality framework is lacking for tensorial theories. Standard deconfinement methods for these theories often yield dual descriptions that suffer from negative R charges or accidental symmetries, complicating reliable duality checks.Motivated by NS5–D5 brane configurations in string theory, I propose that strongly coupled superconformal theories known as quad-CFTs naturally serve as consistent candidate dual descriptions. For antisymmetric tensor theories, consistent dual descriptions emerge from quad-Sp theories via partial flipping and gauging flavor symmetries. Inspired by this success, I conjecture new dual descriptions for symmetric tensor theories using quad-SO theories, again applying partial flipping and gauging.​ Intrinsic features of these quad-CFTs—including their mesonic and baryonic branches, moduli spaces, and deformations—directly reproduce and clarify essential physical properties of the original SU(N) theories. These correspondences provide nontrivial consistency checks of the conjectured dualities, and demonstrate that quad-CFTs constitute a robust framework for constructing dual descriptions and systematically studying the IR behavior of N=1 tensorial gauge theories.

Speaker: Ajit Kumar

67 Navigating the T-Duality Landscape of Little String Theories

In this talk, we explore the phenomenological potential of heterotic line bundle models as a promising framework for deriving the Standard Model from string theory. We present a systematic approach to constrain the low-energy effective theories derived from such compactifications using remnants of anomalous U(1) symmetries to retrieve realistic quarks and leptons masses, mixing patterns and light Higgs. We show that these features emerge in specific regions of moduli space, where vacuum expectation values of geometric moduli and bundle singlets eventually align to suppress unwanted
-parity violating couplings. This work underscores the viability of heterotic line bundle models as a pathway to connecting string theory with observable particle physics.

Speaker: Hamza Ahmed

68 Non-invertible Symmetries and a Categorified Bagger–Witten Line Bundle in Exceptional Holonomy

In Calabi–Yau compactifications, the Bagger–Witten line bundle captures how the $U(1)_R$ symmetry varies over SCFT moduli space. For compactifications on $\mathrm{Spin}(7)$ and $G_2$ manifolds, the worldsheet theories include Ising and tricritical Ising sectors, whose non-invertible fusion categorical symmetries generalize the role of $U(1)_R$. In this talk, I propose a categorified version of the Bagger–Witten line bundle: a stack of module categories over moduli space, encoding the variation of these categorical symmetries. This framework offers new insight into moduli space geometry and the global structure of exceptional holonomy SCFTs.

Speaker: Xingyang Yu

Parallel Session 3

69 The Ins and Outs of Casimir energies on Riemann-flat manifolds

We have used Casimir energies and Riemann-flat manifolds (RFM) to construct an explicit dS5 maximum in M-theory. In this talk I will outline how we did it--in particular, I will present the fully explicit formula we obtain for the Casimir stress-energy in a general RFM, including its higher-dimensional profile; explain how the Casimir energy localizes in particular loci of the RFM, which we call "Casimir branes''; and discuss the exact cancellation between the tension of Casimir branes that sometimes happens due to a spacetime analog of worldsheet Atkin-Lehner symmetry. Throughout the talk I will use our explicit dS5 M-theory maximum as an illustration.

Speaker: Bruno Valeixo Bento

70 Dark Bubble Cosmology in the 0‘B string

We build a novel realization of dark bubble cosmology in non-supersymmetric string theory. Among the simplest models in ten dimensions, the type 0'B orientifold is the unique option which yields a scale-separated construction. The resulting setting produces a logarithmically varying dynamical dark energy, reflecting its holographic counterpart in terms of running gauge couplings. We analyze in detail the phenomenological consequences of the model for particle physics, inflation and late-time cosmology. We find that, although particle physics may be consistently realized, neither early-time nor late-time cosmology are observationally viable

Speaker: Joaquin Masias

71 TBA

TBA

Speaker: Alon Faraggi

72 Fuzzy Axions and Associated Relics

We study fuzzy axion dark matter in type IIB string theory, for axions descending from the Ramond-Ramond four-form in compactifications on orientifolds of Calabi-Yau hypersurfaces. Such models can be tested by cosmological measurements if a significant relic abundance of fuzzy dark matter arises, which we argue is most common in models with small numbers of axions. We construct a topologically exhaustive ensemble of more than 350,000 Calabi-Yau compactifications yielding up to seven axions, and in this setting we perform a systematic analysis of misalignment production of fuzzy dark matter. In typical regions of moduli space, the fuzzy axion, the QCD axion, and other axions have comparable decay constants of f_a \simeq 10^16 GeV. We find that overproduction of heavier axions is problematic, except at special loci in moduli space where decay constant hierarchies can occur: without a contrived reheating epoch, it is necessary to fine-tune initial displacements. The resulting dark matter is typically a mix of fuzzy axions and heavier axions, including the QCD axion. Dark photons are typically present as a consequence of the orientifold projection. We examine the signatures of these models by simulating halos with multiple fuzzy axions, and by computing new cosmological constraints on ultralight axions and dark radiation. We also give evidence that cosmic birefringence is possible in this setting. Our findings determine the phenomenological correlates of fuzzy axion dark matter in a corner of the landscape.

Speaker: Federico Carta

73 Analysis of inflationary models in higher-dimensional uniform inflation

We consider higher-dimensional uniform inflation, in which the extra dimensions expand at the same rate as three-dimensional non-compact space during inflation. We compute the cosmological perturbation in $D+4$ dimensions and derive the spectral index $n_s$ and the tensor-scalar ratio $r$. We analyze five inflationary models: chaotic inflation, natural inflation, quartic hilltop inflation, inflation with spontaneously broken SUSY, and $R^2$ inflation. By combining the results from these models with the Planck 2018 constraints, we discuss that it is not desirable for the extra-dimensional space to expand at the same rate as the three-dimensional non-compact space, except for the case of one extra dimension.

Speaker: Takuya Hirose

15:00 Coffee Break

Parallel Session 1

74 Emergent Strings in type IIb limits of Type IIB String Theory

We discuss the realization of the Emergent String Conjecture in certain infinite distance limits in the vector multiplet moduli space of Type IIB compactifications on Calabi-Yau threefolds. We establish the existence of a critical tensionless string corresponding to a heterotic string on T^2 x K3, in limits of type IIb that correspond to so-called Tyurin degenerations. We do so by combining the properties of the low-energy effective theory as captured in terms of the underlying limiting mixed Hodge structure, as well as the precise geometric degeneration of the Calabi-Yau threefold as described in terms of the underlying geometric mixed Hodge structure.

Speaker: Jeroen Monnee

75 Laplacians in Various Dimensions and the Swampland

TBD

Speaker: Christian Aoufia

76 A finite 6d supergravity landscape from anomalies

TBD

Speaker: Gregory Loges

77 Asymptotics of 5d Supergravity Theories and the Emergent String Conjecture

Using supergravity string probes, we study infinite distance boundaries in the vector multiplet moduli space of 5d N=1 supergravities. By imposing consistency of their worldsheet theories, we derive several constraints on the 5d Chern-Simons couplings, including their non-negativity. These constraints allow us to classify all infinite distance limits without having to assume any geometric origin of the theory. Our findings are in perfect agreement with the predictions of the Emergent String Conjecture and imply that every consistent 5d N=1 supergravity with a non-compact vector multiplet moduli space either descends from six dimensions or comes from string theory.

Speaker: Lukas Kaufmann

78 The Boundary of Symmetric Moduli Spaces and the Swampland Distance Conjecture

For non-compact, locally symmetric moduli spaces ${\cal M}$, the set of geodesics and the geometry of the boundary can be completely characterised using group-theory notions. In particular, geodesics that reach infinite distance (which are a set of measure zero) are associated to rational parabolic subgroups of the isometry group $G$. Under the mild assumptions that ${\cal M}$ has finite volume and that the spectrum of states is complete, we use this relation to prove the swampland distance conjecture for all such spaces ${\cal M}$. Furthermore, the lattice of states forms a representation of $G$, and we show that the convex hull encoding the exponential rate of the leading tower of states becoming light is simply the convex hull of the weights of the representation. For an irreducible representation, this is the Weyl polytope built from the highest weight vector. We classify all such polytopes that are consistent with the emergent string and sharpened distance conjecture, and find that there are only finitely many classes, which we list. For each group only one representation for particles is allowed, and the space-time dimension can only have a fixed value.

Speaker: Bernardo Fraiman

Parallel Session 2

79 Non-geometric string vacua

In this talk, we discuss various aspects of Minkowski vacua arising in the $1^9$ and $2^6$ Landau-Ginzburg Models. In particular, we present fully stabilized $\mathcal{N}=1$ Minkowski vacua and violations of the refined tadpole conjecture. We also comment on symmetry arguments that could potentially explain the existence of flat directions in these models.

Speaker: Muthusamy Rajaguru

80 SymTFT Entanglement and Holographic (Non)-Factorization

Symmetry topological field theories (SymTFTs) have been very useful tools in recent years for studying the generalized symmetries and 't Hooft anomalies of QFTs. When a QFT has a semiclassical holographic dual, there is typically a neat dictionary between the SymTFT data and configurations of various branes in the string background. In this talk, we will address such a dictionary in cases where the AdS spacetime has multiple asymptotic boundaries. A crucial new piece of data will turn out to be the entanglement structure of SymTFT states which, if non-trivial, leads to violations of factorization for partition functions and Hilbert spaces. Applying these considerations to eternal AdS black holes, we show that several conceptual puzzles regarding the conjectured holographic dual to a thermofield double state are resolved. In particular, we construct top-down counterexamples which falsify a conjecture stating that all objects threading the wormhole connecting the two causally disconnected regions are splittable.

Speaker: Ethan Torres

81 (Quadratically) Refined Discrete Anomaly Cancellation

TBA

Speaker: Michelangelo Tartaglia

82 Rediscovering the Standard Model with AI

TBA

Speaker: Pellegrino Piantadosi

83 Searching for new Special Lagrangians with Quality-Diversity Optimization

Special Lagrangian (sLags) submanifolds are crucial objects for string phenomenology and the SYZ conjecture, yet their explicit construction remains a significant challenge in geometry. In this talk, we introduce a novel computational framework to tackle this problem. Using the Fermat Quintic as a primary testbed, our approach leverages a Quality-Diversity (QD) search algorithm to navigate families of parametrized geometries. This method is engineered to simultaneously reward approximations of the sLag condition while maximizing geometric diversity. Our preliminary findings showcase the potential of this QD framework as a powerful new tool in the ongoing search for novel sLag constructions.

Speaker: Yidi Qi

Parallel Session 3

84 Universality in the String Axiverse

Studies of axion effective theories in the type IIB Calabi-Yau landscape have revealed that hierarchies in geometric volumes drive correlations between axion physics and the number of axions in a given model. We provide evidence that distributions of appropriately normalized divisor volumes in the toric hypersurface Calabi-Yau threefolds are universal across this landscape. Furthermore, we show that divisor volumes are the most relevant data to approximate string-derived axion effective theories. Finally, we propose a simple model for the spectrum of normalized divisor volumes and use this model to reproduce results on axion masses and decay constants across the Kreuzer-Skarke axiverse.

Speaker: Junyi Cheng

85 Intersecting D-branes

For decades intersecting D-branes and O-planes have been playing a very important role in string phenomenology in the context of particle physics model building and in the context of flux compactifications. The corresponding supergravity equations are hard to solve so generically solutions only exist in a so-called smeared limit where the delta function sources are replaced by constants. We are showing here that supergravity solutions for two perpendicularly intersecting localized sources in flat space do not exist for a generic metric Ansatz. We show this for two intersecting sources with p = 1, 2, 3, 4, 5, 6 spatial dimensions that preserve 8 supercharges, and we allow for fully generic fluxes.

Speaker: Zheng Miao

86 Warped G2-throats in IIA and uplift dSillusions

Flux compactifications of IIA supergravity on orientifolded G2-manifolds have been argued to allow for classical 3d Minkowski vacua with moduli and scale-separated 3d AdS vacua with full moduli stabilisation. To further uplift these vacua to meta-stable 3d dS vacua using anti-D2 branes, warped throats are desirable. We study the flux-stabilisation of local “CGLP-type” throats in compact G2 spaces, and discuss consistency constraints on anti-brane uplifting. Despite the classical 3d AdS vacua to be free of tachyons, we find that uplifting from anti-branes down warped throats is forbidden.

Speaker: George Tringas

87 Super-hidden Photons and how to find them in the Landscape

A generic feature of string theory compactifications are hidden sectors. In particular, in the Type IIB/F-Theory corner of the landscape, a prominent example is an isolated D3-brane hosting a U(1) gauge field that is spatially separated from a locally realized standard model (SM). In this talk, I argue how 'super-hidden' photons living on such branes generically interact with the SM via spin-dependent interactions mediated by bulk fields. The general mechanism is illustrated in a simple toy model with Pati-Salam gauge group, and we discuss potential phenomenological constraints on such couplings to the visible sector.

Speaker: Jonathan Steiner

88 Chasing the Standard Model within heterotic line bundle constructions

In this talk, we explore the phenomenological potential of heterotic line bundle models as a promising framework for deriving the Standard Model from string theory. We present a systematic approach to constrain the low-energy effective theories derived from such compactifications using remnants of anomalous U(1) symmetries to retrieve realistic quarks and leptons masses, mixing patterns and light Higgs. We show that these features emerge in specific regions of moduli space, where vacuum expectation values of geometric moduli and bundle singlets eventually align to suppress unwanted $R$-parity violating couplings. This work underscores the viability of heterotic line bundle models as a pathway to connecting string theory with observable particle physics.

Speaker: Luca Armando Nutricati

19:30 Conference Dinner

Friday 11 July

08:30 Registration

89 Hidden Supertrace Constraints and UV/IR Mixing

TBD

Speaker: Steven Abel

90 TBA

Speaker: Savdeep Sethi

91 The dark dimension and its interplay with recent cosmological data

TBD

Speaker: Georges Obied

10:30 Coffee Break

92 Non-supersymmetric vacua in string theory and their stability

I will show how to quickly check stability under many non-perturbative decay channels for several old and new non-supersymmetric AdS vacua in type II string theory, on coset spaces, sphere fibrations, and Kähler–Einstein manifolds. I will do so using calibrations, which are more commonly used for supersymmetric vacua. I will also mention how some of the same spaces can be used to produce new AdS solutions for the heterotic SO(16)xSO(16) theory

Speaker: Prof. Alessandro Tomasiello

93 TBA

TBA

Speaker: Irene Valenzuela

12:00 Lunch

94 Spectral Bounds in 6d N=(1,0) Supergravity

TBA

Speaker: Seung-Joo Lee

95 Exploring distant corners of Calabi-Yau moduli spaces

The notion of a string compactification on a smooth Calabi-Yau manifold is only valid in certain "large volume" regions in the moduli space. In this talk we will discuss what can happen in other asymptotic regions of the moduli space where a simple geometric picture does not apply and how one can use physics technology such as gauged linear sigma models (GLSMs) to study those regions.

Speaker: Johanna Knapp

96 An index for flux vacua

TBD

Speaker: Severin Lüst

15:00 Coffee Break

97 A Quantum Cobordism Category

TBD

Speaker: Jacob McNamara

98 6D Anomaly cancellation for discrete gauge symmetries and their UV completion

In this talk, we discuss 6D discrete gauge symmetries and their anomaly cancellation from several perspectives. First, we approach the problem from a field theory viewpoint by lifting fermions and B-fields to the 7D anomaly theory, which allows us to extract non-trivial consistency conditions, refined up to a choice of quadratic refinement. Second, we demonstrate how these conditions can be matched to a Higgsed remnant of a U(1) gauge theory, for a specific fixed choice of quadratic refinement—one that we also show to be realized in the F-theory geometry. By exploiting anomaly inflow on the 2D non-critical strings that couple to the 6D B-fields, along with the modularity of the Type IIA topological string partition function, we extract the corresponding Green-Schwarz-Sagnotti-West couplings from the geometry of torus-fibered Calabi-Yau threefolds. We conclude by highlighting several applications of these discrete anomaly cancellation conditions for both field theory and geometry.

Speaker: Paul-Konstantin Oehlmann

99 Finite Landscape of 6d N=(1,0) Supergravity

TBD

Speaker: Hee-Cheol Kim

100 Classifying Elliptically Fibered Toric Hypersurface CY3s

The largest known set of Calabi-Yau threefolds originates from triangulations of the 473,800,776 four-dimensional reflexive polytopes constructed by Kreuzer and Skarke. Earlier work by Huang and Taylor showed that all but 29,223 of these polytopes admit at least one elliptic fibration. In this talk, we enumerate all such fibrations, finding a total of 2.25 billion fibrations, and classify their fiber and base types. We comment on generic and exotic features of these fibrations, such 6D SCFTs and gauge groups hosted on nontoric divisors. We conclude by discussing elliptic fibrations in the actual Calabi-Yaus built out of these polytopes.

Speaker: Richard Nally