Registration Room: „Aula B” Lecture Room

Welcome Remarks

• Krzysztof Turzynski (University of Warsaw, Poland)

Room: „Aula B” Lecture Room

Higgs boson physics at the LHC

• Andre Sopczak (Czech Technical University in Prague (CZ))

Room: „Aula B” Lecture Room The latest results of Higgs boson measurements in the Standard Model and searches beyond the Standard Model from the ATLAS and CMS experiments are reviewed. This includes searches for additional neutral, charged, and double charged Higgs-like bosons, searches for dark matter produced in association with a Higgs boson, and searches for new physics in Higgs boson production and decay processes. Interpretations are given {within} the hMSSM, a special parameterization of the Minimal Supersymmetric extension of the Standard Model, in which the mass of the lightest Higgs boson is set to the value of 125 GeV measured at the LHC.

Comments on beyond the Standard Model physics and its links to cosmology.

• Stefan Pokorski (University of Warsaw (PL))

Room: „Aula B” Lecture Room Overview

Supercooling in the early Universe

• Bogumila Swiezewska

Room: „Aula B” Lecture Room This talk will discuss various aspects of predicting gravitational-wave signals from supercooled first-order phase transitions in models with classical scale invariance. Motivated by great prospects for observation of such a gravitational-wave signal, and by the consequent opportunities for reconstructing the parameters of the phase transition and the underlying model, I will present the route to improved accuracy in formulating theoretical predictions. I will also comment on the naturalness of such scenarios.

Realising Dark Matter and Pulsar Timing Array via Dark Branes

• Fotis Koutroulis (IFT, Warsaw University)

Room: „Aula B” Lecture Room

Black holes and gravitational waves from slow phase transitions

• Piotr Toczek (University of Warsaw)

Room: „Aula B” Lecture Room Slow first-order phase transitions generate large inhomogeneities that can lead to the formation of primordial black holes (PBHs). We show that the gravitational wave (GW) spectrum then consists of a primary component sourced by bubble collisions and a secondary one induced by large perturbations. The latter gives the dominant peak if $\beta/H_0 < 10$, impacting, in particular, the interpretation of the recent PTA data. The GW signal associated with a particular PBH population is stronger than in typical scenarios because of a negative non-Gaussianity of the perturbations and it has a distinguishable shape with two peaks.

New frontiers of extragalactic astrophysics and cosmology

• Agnieszka Pollo

Room: „Aula B” Lecture Room Galaxies are known to be good but biased tracers of the underlying dark matter field, and the relations between galaxy physical properties and the dark cosmic web are not easy to model. At the same time, all cosmological tests are necessarily based on baryonic tracers - usually related to galaxies. In my talk, I will show recent results from our group illustrating nontrivial dependencies between galaxy evolution, large scale structure and cosmology, and discuss prospects - and pitfalls - with the data from near-future large sky surveys.

Resonant leptogenesis in minimal $U(1)_X$ extensions of the Standard Model

• yuta orikasa

Room: „Aula B” Lecture Room We investigate a general $U(1)_X$ scenario where we introduce three generations of Standard Model (SM) singlet Right-handed Neutrinos (RHNs) to generate the light neutrino mass through the seesaw mechanism after the breaking of $U(1)_X$ and electroweak symmetries. In addition to that, a general $U(1)_X$ scenario involves an SM-singlet scalar field and due to the $U(1)_X$ symmetry breaking the mass of a neutral beyond the SM (BSM) gauge boson Z' is evolved. The RHNs, being charged under $U(1)_X$ scenario, can explain the origin of observed baryon asymmetry through the resonant leptogenesis process. Applying observed neutrino oscillation data we study Z' and BSM scalar induced processes to reproduce the observed baryon asymmetry. Hence we estimate bounds on the $U(1)_X$ gauge coupling and the mass of the Z' for different $U(1)_X$ charges and benchmark masses of RHN and SM-singlet scalar. Finally we compare our results with limits obtained from the existing limits from LEP-II and LHC.

Neutrinos and the Quest for New Frontiers

• Newton Nath

Room: „Aula B” Lecture Room While successful in explaining various natural phenomena, the Standard Model (SM) of particle physics cannot tackle crucial fundamental challenges including non-zero neutrino mass, viable dark matter candidates, and the nature of neutrinos and their novel interactions. In this talk, starting with a brief overview, we will first discuss the current status and unknowns of various neutrino oscillation parameters. A framework based on the “scoto-seesaw” mass mechanism will be discussed to explain neutrino data along with dark matter. We will then focus on neutrino non-standard interactions (NSIs) and their impact on CE\nuNS experiments. Later, this presentation will delve into the capability of the JUNO detector to detect 5.5 MeV solar-axion.

How far can we see back in time in high-energy collisions using charm?

• Laszlo Gyulai (HUN-REN Wigner Research Centre for Physics (HU))

Room: „Aula B” Lecture Room We use open charm production to estimate how far we can see back in time in high-energy hadron-hadron collisions. We analyze the transverse momentum distributions of the identified D mesons from pp, p–Pb and A–A collisions at the ALICE and STAR experiments covering the energy range from $\sqrt{s_{\rm NN}}$ = 200 GeV up to 7 TeV. While the low-momentum part of the spectra can be associated with particles stemming from a thermal equilibrium, the high-momentum regime follows a power-law-like distribution, resulting from perturbative QCD hadron production. Recent non-extensive thermodynamical models, however, are able to successfully describe the spectra within a unified framework [1]. We discuss the consistency of the resulting Tsallis temperature and non-extensivity parameter, and compare them to the ones of light-flavour hadrons. These results allow us to estimate the production time of D mesons in relation to the light-flavour hadrons [2]. [1] G. Bíró, G. G. Barnaföldi, T. S. Bíró, J. Phys. G: Nucl. Part. Phys. 47 (2020) 105002 [2] L. Gyulai, G. Bíró, R. Vértesi, G. G. Barnaföldi, preprint: arXiv:2401.14282 [hep-ph]

Search for new scalars with Z' bosons

• Zoltán Péli (Eotvos Lorand University (HU))

Room: „Aula B” Lecture Room The $U(1)$ extensions of the standard model have the potential to explain several beyond the standard model phenomena at the cost of predicting the existence of $Z'$, a new neutral gauge boson. In the simplest scenario $Z'$ acquires its mass from the spontaneous breaking of a new scalar field, also predicting a new scalar boson $s$. We show that taking into account the combined effects of $s$ and $Z'$ yields a severe exclusion limit on the free parameters of the model.

Supra-massive dark objects and the mass-gap problem

• Vlasios Petousis (Czech Technical University in Prague (CZ))

Room: „Aula B” Lecture Room Until today, the nature of dark matter (DM) remains elusive despite all our efforts, the only we know is that interacts only gravitational. On the other hand, neutron stars (NSs) and black holes (BHs) are the after death remnants of massive stars having big gravitational field. This leads us to the natural assumption that compact objects might contain DM too. By employing the two-fluid model, we discovered a stable area in the mass-radius diagram of a celestial formation consisting of NS matter and DM that is substantial in size. These formations spans hundreds of kilometers in diameter and possesses a mass equivalent to 100 or more times the solar mass. To elucidate, this entity resembles an enormous celestial body of DM, with a NS at its core. In addition, using the same technique and notion, knowing that the region between the most massive NS and the least massive BH is called the “mass gap” we propose a possible explanation for the existence of compact objects within the “mass gap” region. Specifically, we propose that the mass gap region could be bridged by the existence of a hybrid compact object, composed of hadronic and self-interacting, non-annihilating fermionic DM, considering that the interaction between these “two fluids” it's only gravitational. In any case, the present theoretical predictions can, if combined with corresponding observations, shed light on the existence of DM and even more on its basic properties.

Stability of multibrane models

• Marek Olechowski

Room: „Aula B” Lecture Room 5D model with two orbifold 3-branes was originally proposed to address the hierarchy problem. The distance between the branes is usually stabilized via the Goldberger-Wise mechanism. Stability of this construction is related to a 4D scalar mode called the radion. Many different modifications of the simplest set-up have been considered in different contexts. In some models more 3-branes are present in addition to the pair of orbifold branes. Stability of such models was not discussed in much detail. It this talk I will present exact necessary and sufficient conditions for stability of 5D multibrane models with Goldberger-Wise scalar. I will discuss also properties of the corresponding radion(s).

Compact Star Twins

• David Edwin Alvarez Castillo

Room: „Aula B” Lecture Room In this talk I shall present the mass twins compact star phenomenon together with the idea behind their existence and the motivation for searches. I will briefly review the special features in the equation of state (EoS) of the twins as well as their properties as compact stars. Such macroscopical properties can be tested with state-of-the-art multi-messenger astronomical observations. I will discuss the possibility that the HESS J1731-347 object is a compact star twin and the corresponding implications. Furthermore, I will address the study of gravitational wave signals from mergers and from f-modes of twins, as well as their existence as an explanation of very eccentric orbits of binary systems and production of isolated neutron stars. The compact star twins idea can be naturally be generalized to more than two compact stars of the same mass which will feature several phase transitions in the EoS that describes them.

Registration Room: „Aula B” Lecture Room

Presenting the EuPRAXIA Project

• Imre Ferenc Barna (Wigner Research Center)

Room: ”Aula B” Lecture Room EuPRAXIA is the first European project that develops a dedicated particle accelerator research infrastructure based on novel plasma acceleration concepts. Two separate facilities will be built by i nnnovative laser- and beam-driven plasma wakefield acceration schemes. These new kind of mechanism offers a significant reduction in size and possible savings in cost over current state-of-the-art radiofrequency (RF)-based accelerators. EuPRAXIA is one of the projects on the European Strategy Forum on Research Infrastructures (ESFRI) Roadmap of 2021.

Image reconstruction with proton computed tomography

• Zsofia Jolesz

Room: „Aula B” Lecture Room Proton therapy is one of the most effective treatments for cancer, with radiation treatment planning being a crucial element. While photon CT is commonly used for this purpose, it does not provide sufficiently accurate information about proton range, making proton CT a more suitable option for treatment planning. Due to the Coulomb scattering of protons, a key task is the voxel-level calculation of Relative Stopping Power, which requires accurate handling of proton trajectories. Several algorithms have been developed for this purpose. My research focuses on testing, improving, and optimizing a software package that uses the Richardson-Lucy algorithm, developed within the Bergen Proton-CT Collaboration. I conducted the necessary simulations using Geant4 and GATE software. The framework employing the Richardson-Lucy algorithm was optimized using appropriate methods to enhance speed and efficiency. I validated the algorithm's performance and image reconstruction across different energy levels and medical imaging phantoms designed to assess system accuracy. As a result of my work, I successfully optimized the algorithm, significantly reducing computation time. The evaluation of phantom reconstructions confirmed that the algorithm operates with the desired accuracy. My long-term goals include further optimization and ensuring clinical applicability, with a focus on further reducing runtime.

Searches from Cosmological GW in the NANOGrav 15-year dataset

• Rafael Robson Lino dos Santos (NCBJ, Warsaw)

Room: „Aula B” Lecture Room I report on the latest searches for signals of new physics in the NANOGrav 15-year dataset, focusing especially on inflationary and scalar-induced gravitational wave sources. This is based on the NANOGrav collaboration papers 2306.16219 and 2408.10166.

Search for cosmological phase transitions through their gravitational wave signals

• Marek Lewicki (University of Warsaw)

Room: „Aula B” Lecture Room We are currently witnessing the dawn of a new era in astrophysics and cosmology, started by the first LIGO/Virgo/KAGRA observations of Gravitational Waves (GW). Very recently, also the detection of a stochastic background of GWs at very low frequencies was announced by the Pulsar Timing Array collaborations. In this talk, I will discuss how such signals are produced in cosmological phase transitions and examine the possible implications of current data for this source as well as the prospects for detection in the upcoming next generation of GW experiments.

Phenomenology of flavor symmetries

• Janusz Gluza (University of Silesia (PL))

Room: „Aula B” Lecture Room I will discuss flavour symmetries and lepton masses and mixing, focusing on the phenomenology of flavor symmetries and possible signatures in the current and future experiments at the intensity, energy, and cosmic frontiers.

Origin of mass scales in scale-symmetric extension of Standard Model

• Paulina Michalak (University of Warsaw)

Room: „Aula B” Lecture Room The hierarchy problem arises from quantum corrections at ultraviolet scales, which drive the Higgs boson mass to values higher than observed experimentally. One potential solution is to impose conformal or scale symmetry. However, the Higgs mass must still be generated, which can occur through spontaneous breaking of scale symmetry. In this work, we propose a scale-symmetric extension of the Standard Model Higgs sector, where mass scales emerge not through radiative corrections but through the spontaneous breaking of scale symmetry, triggered when the Goldstone boson (dilaton) acquires a vacuum expectation value (VEV). We demonstrate how this VEV is reached through the evolution of fields in the hot early Universe, and show that coupling this theory to gravity provides a stable solution.

EFT for supercooled phase transitions

• Maciej Kierkla (University of Wasrsaw, Poland)

Room: „Aula B” Lecture Room We analyze the role of higher-order thermal corrections for supercooled phase transition, and to what extent they can be computed using dimensionally reduced effective field theory (3D EFT). This framework requires high-temperature (HT) expansion to be valid, which seems challenging due to the presence of supercooling. We show how to reliably use the HT expansion in dimensionally reduced theory for the calculation of bubble nucleation rate, and apply it to a classically scale-invariant model These corrections affect the predictions significantly e.g. transition temperature and scale. We compare new results to the ones obtained using the most common scheme based on the so-called daisy resummation.

Magnetic monopoles in cosmic magnetic fields: acceleration and constraints

• Daniele Perri (SISSA Trieste, Trieste)

Room: „Aula B” Lecture Room Magnetic monopoles are intriguing hypothetical particles and inevitable predictions of theories of Grand Unification. They should be produced during phase transitions in the early universe, but also mechanisms like the Schwinger effect in strong magnetic fields could contribute to the monopole number density. We show how from the detection of intergalactic magnetic fields we can infer additional bounds on the magnetic monopole flux, and how even well-established limits, such as Parker bounds and limits from terrestrial experiments, strongly depend on the acceleration in cosmic magnetic fields. We also discuss the implications of these bounds for minicharged monopoles and magnetic black holes as dark matter candidates. Finally, we apply our primordial bounds to monopoles produced by the primordial magnetic fields themselves through the Schwinger effect, deriving necessary conditions for the survival of the primordial fields.

Bubble-Wall Velocity from Hydrodynamical Simulations

• Mateusz Zych (University of Warsaw)

Room: „Aula B” Lecture Room Terminal velocity reached by bubble walls in cosmological first-order phase transitions is an important parameter determining both primordial gravitational wave spectrum and the production of baryon asymmetry in models of electroweak baryogenesis. We developed a numerical code to study the real-time evolution of expanding bubbles and investigate how their walls reach stationary states. In this talk I discuss the recent results for local thermal equilibrium approximation for which we confirmed that pure hydrodynamic backreaction can lead to steady-state expansion and that bubble-wall velocity in such case agrees very well with the analytical estimates. However, this is not the generic outcome. Instead, it is much more common to observe runaways, as the early-stage dynamics right after the nucleation allow the bubble walls to achieve supersonic velocities before the heated fluid shell in front of the bubble is formed. In order to capture this effect, we generalized the analitical methods beyond the local thermal equilibrium and find a qualitative way to predict whether the runaway is physical, which has a crucial impact on cosmological observables.

Hydrodynamic simulations of accretion in the Reissner-Nordström space-time

• Tomasz Krajewski (Nicolaus Copernicus Astronomical Center)

Room: „Aula B” Lecture Room We performed the first simulations of accretion onto the compact objects in the Reissner-Nordström (RN) spacetime. The results obtained in general relativity are representative of those for spherically symmetric naked singularities and black holes in a number of modified gravity theories.

Phase transition and gravitational waves in maximally symmetric composite Higgs model

• Ignacy Nałęcz (University of Wasrsaw, Poland)

Room: „Aula B” Lecture Room In my talk, I will discuss transitions in a maximally symmetric composite Higgs model with next-to-minimal coset, where a pseudoscalar singlet emerges alongside the Higgs doublet. I will focus on the scenario involving an explicit source of CP violation in the strong sector, which induces a $\mathbb{Z}_2$ asymmetric scalar potential, and consequently leads to nonzero vacuum expectation value for the singlet. The presence of explicit CP violation leads to strong first-order phase transition from a false vacuum to the electroweak vacuum where the pseudoscalar singlet has a non-zero vacuum expectation value. As a result of such phase transitions, the production of potentially observable gravitational waves at future detectors will offer a complementary avenue to probe the composite Higgs models, distinct from collider experiments.

Covariant quantum field theory of tachyons

• Andrzej Dragan

Room: „Aula B” Lecture Room Three major misconceptions concerning quantized tachyon fields, the energy spectrum unbounded from below, the frame-dependent and unstable vacuum state, and the noncovariant commutation rules, are shown to be a result of misrepresenting the Lorentz group in a too small Hilbert space. By doubling this space we establish an explicitly covariant framework that allows for the proper quantization of the tachyon fields eliminating all of these issues. Our scheme that is derived to maintain the relativistic covariance also singles out the two-state formalism developed by Aharonov et al. [Phys. Rev. 134, B1410 (1964)] as a preferred interpretation of the quantum theory.

Preheating and gravitational waves from geometrical destabilization

• Krzysztof Turzynski (University of Warsaw)

Room: „Aula B” Lecture Room Multi-field models of inflation with negative field-space curvature may lead to geometrical destabilization of non-adiabatic, or spectator, scalar perturbations. This phenomenon can occur at the end of inflation, e.g. in alpha-attractor models of inflation, or during inflation. Recent numerical lattice simulations shed light onto dynamics of the coupled scalar perturbations when such geometrical destabilization occurs. In the end-of-inflation geometrical destabilization, a rapid growth of the spectator perturbations can lead to preheating and associated production of gravitational waves, to the extent that alpha attractor T-models can be constrained or even ruled out by present observations. The middle-of-inflation geometrical destabilization turns out a short-lived phenomenon and a negative feedback loop prevents field fluctuations from growing indefinitely. As a result, fields undergoing geometrical destabilization are merely shifted to a new classical configuration corresponding to a uniform value of the spectator field within a Hubble patch.

Gravitational waves from more attractive dark binaries

• Nicholas Orlofsky (University of Warsaw)

Room: „Aula B” Lecture Room The detection of gravitational waves (GWs) has led to a deeper understanding of binaries of ordinary astrophysical objects, including neutron stars and black holes. In this work, we point out that binary systems may also exist in a dark sector with astrophysical-mass macroscopic dark matter. These “dark binaries”, when coupled to an additional attractive long-range dark force, may generate a stochastic gravitational wave background (SGWB) with a characteristic spectrum different from ordinary binaries. We find that the SGWB from planet-mass dark binaries is detectable by space- and ground-based GW observatories. The contribution to the SGWB today is smaller from binaries that merge before recombination than after, avoiding constraints on extra radiation degrees of freedom while potentially leaving a detectable GW signal at high frequencies up to tens of GHz.

Closing Remarks V4 Workshop

• Andre Sopczak (Czech Technical University in Prague (CZ))

Room: „Aula B” Lecture Room

Departure day — no workshop activities planned