P. Lasky (Melbourne U., Australia) 
Title: What's next in gravitational-wave astronomy?
Abstract:
The LIGO-Virgo-KAGRA collaborations have now observed gravitational waves from more than 100 mergers of black holes and neutron stars. I will give an overview of the physics and astrophysics we've learned from the beginning of this new field. I will discuss what comes next, both in terms of potential upcoming discoveries, and the next generation of observatories planned for the 2030s. 

Back

V. Vaskonen (U. of Padova)
Title: Primordial black holes.
Abstract:
In this talk, I will review the formation of primordial black holes and the constraints on their abundance. I will also highlight the potential observational signatures of primordial black holes. In particular, I will discuss the possibility that some of the LIGO-Virgo gravitational wave events originate from primordial black hole mergers, the possibility that the gravitational wave background seen by PTAs is a signature of primordial black hole formation in the early Universe and the possibility that the JWST observations of high-z galaxies are an imprint of a primordial black hole population. 

Back

M. Tortola (Valencia U., IFIC)
Title: Neutrino masses and mixings and beyond
Abstract:
Since the historic discovery of neutrino oscillations, the study of their properties has been performed within a wide variety of experiments. Thanks to this great experimental effort, the determination of neutrino masses and mixings has entered the precision era. However, many challenges remain such as the determination of the ordering of the neutrino mass spectrum, the octant of the atmospheric mixing angle, and a robust measurement of CP violation in neutrino oscillation. Several experiments involving powerful accelerator neutrino sources and very large detectors will try to solve these questions in the near future and also in the longer term. Besides neutrino masses and mixings, the existence of other exotic neutrino properties, such as new interactions with matter or neutrino electromagnetic properties are searched for in a variety of experiments. In that respect, observing neutral-current coherent elastic neutrino-nucleus scattering (CEvNS) at the COHERENT experiment has opened a new window to search for new physics beyond the Standard model. We will discuss the potential of current and upcoming CEvNS experiments to investigate neutrino properties.

Back

J.R. Ellis (CERN and Kings College)
Title: What is the source of the gravitational waves detected by PTA experiments?
Abstract:
The most conservative interpretation of the nHz gravitational waves discovered by NANOGrav and other Pulsar Timing Array (PTA) Collaborations is astrophysical, namely that they arise from supermassive black hole (SMBH) binaries. However, alternative cosmological models have been proposed, including cosmic strings, phase transitions, domain walls, primordial fluctuations and "audible" axions. We compare how well these different hypotheses fit the NANOGrav data, both in isolation and in combination with SMBH binaries, and address the questions: Which interpretations fit the data best, and which are disfavoured? We also discuss experimental signatures that can help discriminate between different sources of the PTA GW signal, including fluctuations in the signal strength between frequency bins, individual sources and how the PTA signal extends to higher frequencies.

Back

G. Barnich (ULB, Brussels)
Title: Lessons from DLCQ for physics at null infinity.
Abstract:
Motivated by issues in the context of asymptotically flat spacetimes at null infinity, we clarify in the simplest example of a massless scalar field in two dimensions several subtleties that arise when setting up the canonical formulation on a single or on two intersecting null hypersurfaces with a special emphasis on the infinite-dimensional global and conformal symmetries, the free data, a  consistent treatment of zero modes, matching conditions, implications for quantization of massless versus massive fields and on a derivation from  first principles of the so-called modified bracket.

Back

Back

W. Buchmuller (DESY)
Title: Baryogenesis -  a piece of a puzzle.
Abstract:
The ratio of the number density of baryons to photons in the universe is a tiny number O(10^-9). It must be explained dynamically and in this way it connects particle physics beyond the Standard Model with the physics of the very early universe. The implications for Higgs physics, dark matter, neutrino physics and gravitational waves are illustrated with several representative examples. Baryogenesis significantly constrains different extrapolations of the Standard Model to shorter distances.

Back

Sanjib Kumar Agarwalla (Institute of Physics, Bhubaneswar, India and  University of Wisconsin-Madison, WI, USA)
Title: Imaging the Earth with Atmospheric Neutrinos
Abstract:
Neutrinos produced in cosmic ray interactions in the atmosphere provide a unique and independent probe to explore the internal structure and composition of the deep Earth, which is complementary to traditional seismic and gravitational measurements and pave the way for multi-messenger tomography of Earth. I will discuss the two different approaches to perform Earth tomography with neutrinos: (i) neutrino absorption tomography, based on partial absorption of a high-energy TeV-PeV neutrino flux as it propagates through Earth and (ii) neutrino oscillation tomography, based on Earth matter effects due to the coherent forward scattering of multi-GeV neutrinos with the ambient electrons modifying neutrino oscillation patterns. I will subsequently show how well the DeepCore detector, a densely instrumented sub-array of the IceCube neutrino observatory at the South Pole, can observe these Earth matter effects in atmospheric neutrino oscillations using 9.3 years of data. We will further demonstrate that these matter effects in oscillations of atmospheric neutrinos can be used to establish the layered structure inside Earth and measure the mass of Earth and mass of core. I will conclude my talk discussing the remarkable physics reach of a new extension of DeepCore to be deployed in the Antarctic summer of 2025/26, called the IceCube Upgrade.
Back

S. Parameswaran (U. of Liverpool)
Title: String Cosmology: from the Early Universe to Today.
Abstract:
I'll give some taste of applications of string theory to cosmology, from primordial times to the present-day accelerated expansion.  Time permitting, I'll discuss the main challenges of moduli stabilisation, inflation in string theory, the impact of string theory on post-inflationary dynamics, dark matter and dark energy, drawing connections with swampland conjectures, and emphasise possibilities for novel particles, excitations, and opportunities for observations.

Back

C. Herdeiro (U. Aveiro, Portugal)
Title: Testing the Kerr hypothesis: universality, imitators and dynamical signatures.
Abstract:
To what extent are all astrophysical, dark, compact objects both black holes (BHs) and described by the Kerr geometry? We embark on the exercise of defying the universality of this remarkable idea, often called the "Kerr hypothesis". After establishing its rationale and timeliness, we define a minimal set of reasonability criteria for alternative models of dark compact objects. Then, as proof of principle, we discuss concrete, dynamically robust non-Kerr BHs and horizonless imitators, that 1) pass the basic theoretical, and in particular dynamical, tests, 2) match (some of the) state of the art astrophysical observables and 3) only emerge at some (macroscopic) scales. These examples illustrate how the universality (at all macroscopic scales) of the Kerr hypothesis can be challenged

Back

E. O Colgain (ATU, Sligo, Ireland)
Title: Is H0 a constant in Lambda-CDM cosmology? 
Abstract:
I will outline a natural diagnosis of the Hubble and S8 tension problems in terms of redshift dependent cosmological parameters. If true, this is not a resolution to the problem, but it simply provides confirmation that the model has broken down. I comment on the difficulties processing these ideas in the traditional Bayesian framework.

Back

Hep-ph

S. Ansarifard (IPM)
Title: The light pseudo-scalar lepton interaction inside the Sun
Abstract:

Back

J. Turner (Durham U)
Title: Primordial Black Holes and the early universe.
Abstract:
Primordial black holes, which could have potentially formed after cosmic inflation, can have significant implications for the early Universe's development. These black holes, which may have differing mass and spin, undergo evaporation due to Hawking radiation at different points in cosmic history. In this presentation will explore the potential impact of this evaporation on various cosmological observables, including the creation of matter-antimatter asymmetry, dark radiation, and dark matter.
Back

J. Herrero-Garcia (Valencia U. (IFIC))
Title: An EFT approach to lepton and baryon number violation.
Abstract:
In this presentation, I will discuss lepton and baryon number violation using an Effective Field Theory (EFT) approach. In particular, in the first part of the talk, I will analyse the generation of tree-level Majorana neutrino masses by the introduction of new scalar multiplets at the electroweak scale, which acquire vacuum expectation values (VEVs). We will elucidate the underlying UV completions for these effective operators, specifically the new seesaw models, and investigate their impact on neutrino masses, including contributions at the loop level. We will discuss the phenomenology of these scenarios, including constraints from Electroweak Precision Tests, Lepton Flavor Violation, and colliders. In the second part of the talk, I will explore nucleon decays using SMEFT operators up to dimension 9. We will present estimates for the rates of various nucleon decay channels and use these to extract model-independent lower limits on the energy scale associated with these processes. Additionally, we will investigate potential correlations among processes.

Back

A. Ahmed (MPIK Heidelberg)
Title: Light hidden sectors, neutrino masses and dark matter.
Abstract:
We present a class of models in which the hidden sector is conformal in the ultraviolet, and the compositeness scale lies at or below the weak scale. The hidden sector interacts with the standard model through the neutrino portal. In this framework, dark matter is the lightest stable composite state of the hidden sector. When the hidden sector is in thermal equilibrium with the Standard Model, the dark matter relic abundance is determined by annihilation into final states containing neutrinos through freeze-out mechanism. However, when the hidden sector is out of equilibrium with the Standard Model, dark matter is produced through the freeze-in mechanism. The neutrino portal also leads to the generation of neutrino masses through the inverse seesaw mechanism, with composite hidden sector states playing the role of the singlet neutrinos. We construct a holographic realization of this framework based on a five-dimensional warped geometry and study its phenomenology.

Back

N. Bozorgnia (Alberta U.)
Title: The Influence of the LMC on dark matter direct detection.
Abstract:
The Large Magellanic Cloud (LMC) can significantly impact the dark matter halo of the Milky Way, and boost the dark matter velocity distribution in the Solar neighborhood. Cosmological simulations that sample potential Milky Way formation histories are powerful tools, which can be used to characterize the signatures of the LMC’s interaction with the Milky Way, and can provide crucial insight on the LMC’s effect on the local dark matter distribution. I will discuss the influence of the LMC on the local dark matter distribution in state-of-the-art cosmological simulations, and its implications for dark matter direct detection. 

Back

Hep-th

R. Casadio (Bologna Uni)

A. Mollabashi (IPM)
Title: Timelike Entanglement Entropy.
Abstract:
Motivated by the geometrical understanding of quantum information measures in AdS/CFT, I will introduce a two-state generalization of von Neumann entropy known as pseudo-entanglement entropy as well as a novel quantity corresponding to timelike regions on the CFT side which we call "timelike entanglement entropy" (TEE). It turns out that TEE is a special case of pseudo-entanglement entropy. Concrete definitions on the CFT side together with a prescription to calculate TEE in 2d free quantum field theories will be introduced, which contains some clues about how to understand TEE in quantum information theory. I will also introduce our first version of a holographic prescription to calculate TEE in AdS3/CFT2 and address how TEE in AdS3/CFT2 is related to EE in dS3/CFT2. 

Back

A. Seraj (IPM)
Title: The Infrared triangle in Fracton gauge theory
Abstract:

Back

A.A. Parvizi (IPM)
Title: Hydrodynamics at Causal Boundaries.
Abstract:
In many physical scenarios, it is necessary to describe physics in the presence of a boundary. In such cases we should account for the degrees of freedom (d.o.f.) that reside on the boundary and study their dynamics. This talk focuses on the boundary d.o.f. and their dynamics in a gravitational theories on a spacetime with  timelike and null boundaries. We study 3-dimensional gravity and explore the solution phase space, boundary charges and their algebra. Three of these charges generalize the Brown-York charges to any causal boundary, and are related to the boundary metric components. They also lead to a fluid description of the causal boundary. When the causal boundary is the asymptotic boundary of the 3d AdS or flat space, we recover the conformal or conformal-Carrollian asymptotic hydrodynamics, respectively.

Back

V. Taghiloo (IPM)

C. Zwikel (Perimeter Inst.)
Title: The partial Bondi gauge: asymptotic charges and gauge fixing.
Abstract:
In this talk, I will discuss the future null boundary of asymptotically flat spacetimes in four dimensions. I will introduce the partial Bondi gauge that include as particular cases both the usual Bondi gauge and the Newman-Unti gauge. The partial Bondi gauge exhibits additional symmetries. I will show that two of them possess non-vanishing charges, rendering them physically relevant.

Back

Cosmology

E. Di Valentino (Uni. of Sheffield)
Title: Unresolved Anomalies and Tensions in the Standard Cosmological Model.
Abstract:
The standard Lambda Cold Dark Matter cosmological model has been incredibly successful in explaining a wide range of observational data, from the cosmic microwave background radiation to the large-scale structure of the universe. However, recent observations have revealed a number of inconsistencies among the model's key cosmological parameters, which have different levels of statistical significance. These include discrepancies in measurements of the Hubble constant, the S8 tension, and the CMB tension. While some of these inconsistencies could be due to systematic errors, the persistence of such tensions across various probes suggests a potential failure of the canonical LCDM model. I will examine these inconsistencies and discuss possible explanations, including modifications to the standard model, that could potentially alleviate them. However, I will also discuss the limitations of these proposed solutions and note that none of them have successfully resolved the discrepancies.

Back

E. Ebrahimian (ICTP)

Back

G. Geshnizjani (Uni. of Waterloo)
Title: On the initial singularity and extendibility of flat quasi-de Sitter spacetimes.
Abstract:
Inflationary spacetimes have been argued to be past geodesically incomplete in many situations. However, whether the geodesic incompleteness implies the existence of an initial spacetime curvature singularity or whether the spacetime may be extended (potentially into another phase of the universe) is generally unknown. Both questions have important physical implications. In this talk, we take a closer look at the geometrical structure of inflationary spacetimes and investigate these very questions. I will first discuss classifying which past inflationary histories have a scalar curvature singularity and which might be extendible and/or non-singular in homogeneous and isotropic cosmology with flat spatial sections. Then, briefly go over derivation of a rigorous extendibility criteria of various regularity classes for quasi-de Sitter spacetimes that evolve from infinite proper time in the past. Finally, I will argue that beyond homogeneity and isotropy, special continuous extensions respecting the Einstein field equations with a perfect fluid must have the equation of state of a de Sitter universe asymptotically. An interpretation of these results is that past-eternal inflationary scenarios are most likely physically singular, except in situations with very special initial conditions.

Back

M.H. Namjoo (IPM)
Title: Tail diversity from inflation.
Abstact:
The tail of the distribution of cosmological primordial fluctuations is of interest, from both theoretical and observational perspectives. In particular, it is relevant for accurately evaluating the primordial black hole (PBH) abundance, which is sensitive to the likelihood of realization of large fluctuations. In this talk, I will first advocate the non-perturbative form of the so-called \delta N formalism as a method to estimate the probability distribution function (PDF) of primordial fluctuations and discuss several subtleties that may arise due to the consideration of large fluctuations. Next, I will show that there is a diverse zoo of possible tails from inflation so that, generally, a model-dependent and non-perturbative study of the PDF of the primordial fluctuations seems inevitable concerning PBH abundance.

Back

V. De Luca (Pennsylvania U.)
Title: Superfluid dark matter around black holes.
Abstract:
The theory of superfluid dark matter is based on sub-eV, self-interacting, bosons which may undergo Bose-Einstein condensation at the center of galaxies, thus creating a superfluid homogeneous core. We show how the superfluid density profile changes when massive black holes sit within these environments, giving rise to dark matter spikes whose slopes depend on the bosons self-interactions. Finally, we discuss the role of dynamical friction in the evolution of black hole binaries moving within the superfluid. 

Back

S. Jazayeri (TBC)
Title: Cosmological Phonon Collider.

Back