Conveners
Contributed talks
- Lucas Pinol
Contributed talks
- Sebastien Renaux
Contributed talks
- Nassim Bozorgnia (York University, University of Alberta)
Contributed talks
- Julien Lavalle (LUPM (CNRS / Univ. Montpellier))
Contributed talks
- Diego Blas (ICREA/IFAE)
Contributed talks
- Giulia Cusin
Contributed talks
- Alain BLANCHARD
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Sรฉbastien Renaux-Petel27/04/2026, 14:00
The wavefunction of the universe contains the full information about primordial fluctuations. I will show how to determine it in a non-perturbative manner in a large class of inflationary scenarios, using the example of models with small and rapid oscillations in the inflaton potential. Our study reveals a profound asymmetry between maxima and minima of the density fluctuations, and indicates...
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Arthur Poisson (IAP)27/04/2026, 14:20
In many inflationary scenarios, primordial correlation functions are encoded in late-time observables in de Sitter spacetime, where even the simplest processes already involve highly nontrivial time integrals. I will show that this difficulty can be overcome by introducing a new momentum-space representation adapted to de Sitter isometries. This construction is based on diagonalizing the...
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Nathan Belrhali27/04/2026, 14:30
The generation of primordial density inhomogeneities from the inflaton
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quantum fluctuations is a crucial prediction of inflation. The correlation
functions of these quantum fluctuations, called cosmological correlators,
can be studied in a perturbative framework. These fluctuations can be
mathematically described as quantum massive fields that propagate in a de
Sitter space-time. However,... -
Lisa Mickel (Institut d'Astrophysique de Paris (IAP))27/04/2026, 14:40
In the quest to establish possible imprints of quantum gravity we consider so-called minisuperspace models that should be understood as a low energy limit of a full quantum gravitational theory. Starting from a bouncing minisuperspace model that resolves the big bang singularity, we will relax the assumption that the state of the quantum universe has to correspond to a single highly...
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Sebastian Trojanowski27/04/2026, 15:00
Neutrinos offer a promising window into new physics, and recent data prompt a re-evaluation of their role in the early universe. Neutrino (ฮฝ) portals facilitate thermal dark matter (DM) production, representing one of the few remaining benchmarks in the freeze-out paradigm, yet they remain exceptionally difficult to probe. In this talk, we review the current status of the ฮฝDM portal, focusing...
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Martha Ulloa Calzonzin (University of Florida)27/04/2026, 15:20
The B-Mesogenesis mechanism aims to explain the baryon asymmetry of the Universe and dark matter through the CP violating oscillations and subsequent decays of $B$-Mesons in the early Universe at times right before BBN, $T \simeq (5-20)\,{\rm MeV}$. In this work, we point out that the photo-disassociation process $\gamma+B^0\to B^{0\star}$ that was not accounted for in the original studies is...
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Mattia Dubbini (Universitร di Camerino)27/04/2026, 15:30
We investigate the theory of spontaneous baryogenesis, considering two extensions to the scalar paradigm and proposing a vectorial and LIV version of the model. Concerning the scalar paradigm, firstly we generalize the minimal theory introducing a non-minimal coupling between the inflaton field and the scalar curvature. This modifies the effective mass squared of the inflaton and accordingly...
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Antonio Racioppi (National Institute of Chemical Physics and Biophysics (EE))27/04/2026, 15:40
We propose a new mechanism for inflationary model building in the framework of metric-affine gravity. Such a mechanism involves an inflaton non-minimally coupled with the Holst invariant. If the non-minimal coupling function has a zero point and it is very steep at that same point, the corresponding inflaton kinetic function will feature a quasi-pole behaviour, implying a canonically...
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Simรฉon Vareilles27/04/2026, 16:30
In this talk, we quantitatively characterise the phase of primordial perturbations from inflation to cosmic microwave background scales. Our goal is to analyse how the phase of those perturbations evolve through the entire expansion history of the universe and to identify theoretical reference values that can be tested against future observations.
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To achieve this, we study the quantum... -
Ameek Malhotra27/04/2026, 16:40
The formalism of Bayesian model selection provides an elegant way of ranking different physical models in terms of how compatible they are with a given set of observed data. However, its practical application is often hampered by the challenge of having to compute the Bayesian evidence - a multi-dimensional integral over the product of likelihood and prior probability which may become...
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Mubarak Mohammed (UCLouvain-CP3)27/04/2026, 17:00
The relic abundance of Dark Matter (DM) produced via thermal freeze-in is sensitive to the thermal history during and after cosmic reheating. In minimal models, this opens up the possibility to make predictions for collider observables by combining the requirement to match the DM relic abundance with observations of the Cosmic Microwave Background (CMB). We assess the impact of thermal...
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Prof. Saeed Rastgoo (University of Alberta)27/04/2026, 17:10
I will talk about certain mainstream models of quantum black holes in both loop quantum gravity and generalized uncertainty principle approaches to quantum gravity, and propose some of the multimessenger test that could reveal (or refute) their quantum nature. These tests include electromagnetic and gravitational wave-related phenomena, and I will discuss the expected results in each case if...
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Gabriele Bianchini (University of Camerino)27/04/2026, 17:30
Quasi-periodic oscillations (QPOs) observed in the X-ray emission of accreting compact objects are among the most promising astrophysical messengers of strong-field gravity. Yet, despite decades of observations, their physical origin remains debated, and the most established framework to interpret them, the relativistic precession model (RPM), shows persistent observational tensions, including...
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Alain BLANCHARD28/04/2026, 14:00
Although the existence of dark matter is widely accepted, its true nature remains unknown, motivating alternative explanations such as Modified Newtonian Dynamics (MOND). MOND modifies Newtonโs laws for low accelerations (below $a_0$) and generally reproduces the flat rotation curves of galaxies.
However, recent Gaia data reveal a declining rotation curve in the Milky Way, which...
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Sonali VERMA (ULB, Brussels)28/04/2026, 14:20
In this talk, I will show how measurements of the intergalactic medium (IGM) temperature from the Lyman-ฮฑ forest can be used to constrain long-lived dark sector particles. Such particles deposit energy into the IGM through decays to Standard Model states, thereby modifying the thermal history of the Universe. I will also revisit constraints on these models from Planck CMB measurements of the...
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Stefan Vogl (University of Freiburg)28/04/2026, 14:40
Supernova explosions are extreme cosmic events that may impact not only ordinary matter but also dark matter (DM) halos. In this talk, I explore the possibility that a fraction of supernova energy is released as dark radiation, which could transform a cuspy DM halo into a cored one, potentially explaining observed cores in some dwarf galaxies. Alternatively, limits on DM core sizes provide...
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Ahmad Alachkar (CEA IPHT)28/04/2026, 15:00
Axion dark matter can modify electromagnetic phenomena through its coupling to photons, leading to new signatures in precision experiments. In the presence of an external magnetic field, the axionโphoton interaction acts as an effective electromagnetic source that generates oscillating fields inside a cavity. Previous work by Brax and Brun showed that this mechanism can produce both classical...
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Baraa YAHYA (IPhT (CEA-SACLAY))28/04/2026, 15:20
The piezoaxionic effect enables the conversion of axion-induced spin-dependent forces in polarized nuclei into measurable voltages within piezoelectric crystals. A heterodyne detection scheme is introduced in which controlled nuclear spin precession mixes the axion oscillation frequency with the nuclear Larmor frequency. This process generates sideband signals at shifted frequencies, allowing...
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Alessandro Lella28/04/2026, 15:30
Exotic scalars and vectors coupled to nucleons and muons can be copiously produced in cold isolated neutron stars (NSs). In these environments, the milder temperature dependence of their emissivity compared to neutrinos magnifies significantly the effect of these novel exotic particles on the cooling process of such stars. The absence of traces of exotic cooling for a well-measured sample of...
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Angus Spalding (Univeristy of Southampton)28/04/2026, 15:50
I will show that spectral features of a gravitational-wave background can directly determine Lagrangian parameters of beyond-the-Standard-Model particles, independently of the gravitational-wave production mechanism. Long-lived particles generically induce a temporary period of early matter domination in the thermal history of the Universe, which imprints two characteristic frequencies in any...
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Nudลพeim Selimoviฤ (INFN Padova)28/04/2026, 16:30
I will present the construction and phenomenology of novel portals between the Standard Model and dark sectors, arising from topological operators in chiral perturbation theory. The first example is based on a mixed WessโZuminoโWitten term that uniquely connects three QCD pions to two dark pions, leading to a consistent framework for light thermal inelastic dark matter with suppressed direct...
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Jordan Koechler (INFN Turin)28/04/2026, 16:50
Cosmic-ray antinuclei, in particular antideuterons ($\overline{\rm D}$) and antihelion-3 (${}^3\overline{\rm He}$), are among the most promising messengers for indirect dark matter (DM) searches. Their interest arises from the strong suppression of secondary production in cosmic-ray interactions with the interstellar medium at kinetic energies $K\sim 0.1โ1$ GeV/n, where the expected...
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Dr Arpan Kar (LPTHE, Sorbonne University, Paris)28/04/2026, 17:10
Indirect searches for Dark Matter (DM) particles with mass in the MeV - GeV scale have received significant attention lately. Pair-annihilations of such DM particles in the Galaxy can give rise to MeV - GeV gamma-rays via prompt emission, sub-GeV e+e-'s in cosmic-rays, as well as a broad photon spectrum ranging from X-rays to soft gamma-rays, produced by the secondary emissions from DM induced...
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Thรฉo Parรฉ (LUPM)28/04/2026, 17:30
We explore the gravitational heating of exoplanetary systems by dark matter substructures of different kinds (primordial black holes -- PBHs, ultra-compact -- UCMHs, or classical subhalos). In this context, the scales of the dark objects probed are of the same order as the orbital radii of planets of interest. Distant exoplanets are quite sensitive to heating processes because less bound to...
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Nahuel Ferreiro Iachellini (University of Milano-Bicocca)28/04/2026, 17:40
Core-collapse Supernovae (SN) are critical astronomical events where nearly the entire star's binding energy is emitted as neutrinos. Thanks to their extreme conditions, SN are also incredible laboratories for testing new Physics and could produce a wealth of Beyond Standard Model Particles. RES-NOVA is pioneering a new approach to for the detection of SN neutrinos, introducing cryogenic...
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Jan Schuette Engel (UC Berkeley)28/04/2026, 17:50
Leptogenesis has become one of the leading theories to explain the baryon asymmetry of the universe. On the other hand the existence of non-zero but tiny neutrino masses has been established through neutrino oscillation experiments. The smallness of the neutrino masses can be understood by introducing heavy right-handed neutrinos. If such neutrinos were produced in the early universe and...
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Isabela Santiago de Matos (University of Portsmouth)29/04/2026, 14:00
I will present our recent work where we detected for the first time cross-correlations between gravitational wave sources and galaxies, at 5.9$\sigma$. We analysed the GWTC-3 and GLADE+ catalogs with a novel technique called Peak Sirens. We obtained the first measurement of the Hubble constant from this method, and the first bounds whatsoever on the gravitational wave clustering bias. This...
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Alessandro PEDROTTI29/04/2026, 14:20
We explore the tomographic angular cross-correlation between gravitational-wave and galaxy catalogs as a probe of late-time cosmology. Focusing on next-generation interferometers combined with the Euclid photometric survey, we forecast constraints on the Hubble constant, Matter density parameter and other cosmological parameters.
Our analysis accounts for realistic GW populations,...
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Matteo Schulz29/04/2026, 14:30
Multi-probe techniques have proven to be powerful tools in modern cosmology.
By combining different observational tracers, they break degeneracies and provide new ways to gain insights into the large-scale structure (LSS) of the Universe and its evolution.In this talk, we explore the potential of cross-correlation between gravitational waves (GWs) and 21cm intensity mapping from neutral...
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Alessandro AGAPITO (Aix-Marseille Universitรฉ)29/04/2026, 14:40
The rapidly growing field of dark siren cosmology, driven by advances in Gravitational-Wave (GW) detection campaigns and galaxy surveys, is progressing toward independent and increasingly precise measurements of the Hubble constant. As statistical uncertainties shrink, it becomes crucial to control and eliminate emerging systematics in order to address cosmological and astrophysical...
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Vasco GENNARI (L2IT)29/04/2026, 14:50
Gravitational-wave observations provide a unique window into both black hole populations and cosmology. Using the latest transient catalog, GWTC-4, we investigate the presence of structure in the primary black hole mass distribution through agnostic modelling and compare the results with parametric approaches. We show that the ability to resolve specific features in the mass spectrum plays a...
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Tom BERTHEAS (L2IT, LPENS)29/04/2026, 15:00
Spectral-sirens inference enables the extraction of cosmological parameters from gravitational-wave data alone, without electromagnetic counterparts or galaxy catalogs. We introduce new parametric mass functions for the binary black hole population that capture significant structure across the mass spectrum and are moderately favoured by Bayesian evidence over simpler models. Analysing the...
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Andrea Cozzumbo (Gran Sasso Science Institute)29/04/2026, 15:10
Recent DESI results, combined with other cosmological probes, have revived interest in dynamical dark energy, hinting at phantom crossing and a phantom regime at $z \gtrsim 1$. These observations have brought renewed attention to a class of modified gravity (MG) models consistent with current data but exhibiting rich phenomenology beyond $\Lambda$CDM. Several of these theories introduce a...
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Martin Teuscher29/04/2026, 15:20
We consider the gravitational wave (GW) background induced by arbitrary source fields that are amplified during inflation. We first conduct a very general analysis where the associated tensor spectral index $n_T$ is shown to be given, under minimal assumptions, by a simple and ready-to-use formula. Remarkably, we demonstrate that during slow-roll inflation $n_T$ becomes completely independent...
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Alina Mierna29/04/2026, 15:30
A variety of mechanisms in the early Universe lead to the generation of gravitational waves (GWs). In this talk, I will present a novel source of GWs generated by vacuum fluctuations after inflation. Since gravitons are minimally coupled, their quantum creation takes place during inflation but is absent in an unperturbed Universe during the radiation-dominated epoch, as they behave as...
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Maryam Aghaei Abchouyeh29/04/2026, 15:40
Core-collapse supernovae (CC-SNe) mark the end of the life of massive stars, leaving behind a compact remnant. EM observations alone cannot resolve the astronomical conundrum of identifying the nature of CC-SNe remnant and central engine: neutron star (NS) or black hole (BH). This resolution may come through the radically new window of gravitational wave observation. Conventionally, the...
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Elena Colangeli (ICG - University of Portsmouth)29/04/2026, 15:50
With an increasing number of detections, gravitational waves (GWs) from compact binary coalescences are now an established probe for tests of General Relativity (GR) on cosmological scales. A common test for deviations from GR with GWs involves constraining the ratio of luminosity distance from GWs and the standard electromagnetic (EM) luminosity distance. This usually relies on specific...
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Dr Charles DALANG (Ecole Normale Supรฉrieure)29/04/2026, 16:30
In general relativity, gravitational waves (GW) follow null geodesics, whereas in alternative theories of gravity they may propagate along timelike geodesics. Depending on the form of the dispersion relation, this can produce amplitude distortions in chirping signals. We demonstrate this effect for the case of massive gravitons, showing that dispersion modifies the amplitude of gravitational...
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Pierre Fleury (CNRS, Laboratoire Univers et Particules de Montpellier)29/04/2026, 16:50
When a massive foreground galaxy lies in front of another, more distant, background galaxy, strong gravitational lensing produces spectacular images such as Einstein rings. The detailed morphology of an Einstein ring depends not only on the gravitational field of the main deflector, but also on all the perturbations along the line of sight. As it turns out, both effects can be distinguished,...
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Giacomo QUEIROLO29/04/2026, 17:10
Recent studies uncovered several aspects of strong gravitational lenses that make them useful tools for cosmology. One example is the weak-lensing shear induced by structures along the strong lensโs line of sight (LOS). This observable carries information about the mass distribution in the Universe and therefore represents a valuable cosmological probe.
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While the theoretical feasibility of... -
Emma BRUYERE (IAP)29/04/2026, 17:20
Waves propagating through a gravitational potential exhibit wave-
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optics effects when their wavelength is not significantly smaller than the lensing scales. We study the propagation of a scalar wave, governed by the Klein-Gordon equation in curved spacetime, to focus on effects on amplitude and phase, while leaving aside the issue of wave polarization which affects electromagnetic and... -
Lukasz Bunio (University of Manchester)29/04/2026, 17:30
We consider two extended theories of gravity involving non-minimally coupled scalar fields and investigate their influence on galactic scales. To do so, we linearise the equations of motion for the scalar fields, accounting for their dependence on curvature scalars. In this way, we recover known results and are able to extract the modifications over Einstein gravity due to the presence of...
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Thomas Montandon (Laboratoire Univers et Particules de Montpellier)29/04/2026, 17:40
Decaying dark matter (DDM) provides a well-motivated extension of $\Lambda$CDM, in which two-body decays -- characterized by a decay rate $\Gamma$ and velocity kick $v_k$ -- naturally suppress structure growth and lead to lower clustering amplitudes consistent with weak lensing measurements of $S_8$. Previous analyses combining Planck, BAO, and weak lensing data identified viable parameter...
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Saba Rahimy (Swansea University)29/04/2026, 18:00
The dark sector represents the elusive nature of dark matter and dark energy. Possible sources of the dark sector have long been studied, and with recent data releases from the Dark Energy Spectroscopic Instrument (DESI), interest in scalar field sources for the dark sector has been revived. This talk presents recent work examining scalar fields sourcing the dark sector, with a focus on the...
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Dr David Andriot (LAPTh, CNRS)30/04/2026, 14:00
Dark energy is currently being observed with unprecedented precision. Several cosmological models can for now fit this data. But only some of them can be obtained from string theory: this offers an interesting theoretical prior. We will review to what extent a cosmological constant or an exponential quintessence can be obtained from string theory. Eventually, we will focus on...
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Elsa Teixeira (Laboratoire Univers et Particules de Montpellier, University of Montpellier)30/04/2026, 14:20
The persistent discrepancies between predictions of the standard cosmological model and high-precision measurements across multiple probes remain a significant challenge in modern cosmology. Over the past decade, mounting evidence for tensions in key cosmological parameters - derived through both model-dependent and independent methods - has motivated the exploration of extensions to the...
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Giulia Borghetto (University of Swansea)30/04/2026, 14:40
Recent cosmological observations suggest possible deviations from a cosmological constant, pointing toward a dynamical nature of dark energy. Quintessence models, which assume a slowly rolling scalar field, provide a compelling theoretical framework to explain this late time evolution in the dark energy equation of state. However, identifying the correct form of the quintessence potential...
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Basheer KALBOUNEH30/04/2026, 14:50
In the standard cosmological model, the expansion is expected to be statistically isotropic around any observer. Here, we test this prediction in the local Universe through an analysis of the expansionโrate fluctuation field reconstructed from the Cosmicflows-4 distance data.
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We perform analyses up to redshift $z=0.1$ and examine not only the dipole, commonly associated with bulk flows in... -
Dr Marie-Noรซlle Cรฉlรฉrier (Observatoire de Paris-PSL)30/04/2026, 15:10
In the current era of precision cosmology, the $\Lambda$CDM model, despite its stunning successes, appears insufficient to represent our actual Universe. Owing to the tensions occuring between theory and observations, it appears that a more precise representation of the local universe is mandatory. Since General Relativity (GR) is the best theory currently available to describe gravitation...
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Maharshi SARMA30/04/2026, 15:30
Precision cosmology suggests that late-time inhomogeneities may no longer be treated as small corrections to the FLRW paradigm. Moreover, recent observational hints of axisymmetric anisotropies in the local expansion rate further motivate analyses beyond linear perturbation theory. Motivated by these issues, the framework called "Covariant Cosmography'' is adopted which describes the...
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Maurice van putten (Sejong University)30/04/2026, 15:40
A dynamical dark energy is derived from the scaling dimension two in UVIR-consistency between a bare cosmological constant with Big Bang cosmologies. The resulting Hubble expansion predicts the Hubble constant H0 to be $\sqrt{6/5}$ times the H0 in Planck-$\Lambda$CDM analysis of the CMB. Expressed equivalently in $w(a)$CDM, this new Hubble expansion predicts a phantom crossing at redshift...
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Jessica Santiago30/04/2026, 15:50
We present a new analysis of cosmic dipole anisotropy using gamma-ray bursts (GRBs) as high-redshift standardizable candles. GRBs are ideal probes for testing the cosmological principle thanks to their high luminosity, wide redshift range, and nearly isotropic sky coverage. For the first time, we employ the luminosity-time (L-T) relation, corrected for redshift evolution, to standardize a...
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Francois BOUCHET30/04/2026, 16:10
CMB measurements keep progressing fast and contribute to cosmological advance in a major way. I propose to review the status of the field, making sure that contrary to many speakers, I fully cover the contributions and plans for SPO since I am part of it (NB: SPO = south Pole telescope+Bicep Keck). I will also review of course the status of ACT SO, and Litebird (which I am also part of). I...
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Dr SUHAIL KHAN (Centre for Theoretical Physics,Jamia Millia Islamia)
We study the phenomenology of a feebly interacting sterile neutrino dark matter candidate in a low-scale Type-I seesaw framework extended by an additional scalar doublet. The second Higgs doublet couples exclusively to right-handed neutrinos and lepton doublets, generating the neutrino Dirac mass, while the Standard Model--like Higgs is responsible for the masses of the remaining...
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Prof. Bivudutta Mishra (BITS-Pilani, Hyderabad Campus)
Scalar-tensor theories have shown great potential in inducing tailored modifications compared to cosmic evolution in the $\Lambda$CDM model. We reconsider quintessence models in this work in the context of three driving potentials. We center the action of these models in the late Universe which leaves early $\Lambda$CDM cosmology unchanged. The effects show the potential of producing a faster...
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