GGI workshop: Exploring New Frontiers in Cosmology

Liste des Contributions

141. Cosmology with Torsion and Nonmetricity

Ilaria Andrei

10/07/2026 14:00

Talk at the school (week 1)

Student Talks

Metric affine gravity (MAG) represents an extension of general relativity (GR) in which an independent connection other than the Levi-Civita one is present. In MAG there are three tensors describing the geometry of spacetime, curvature, torsion and nonmetricity. And two tensors related to matter's behaviour, the stress energy tensor and the hypermomentum. After reviewing the main features of...

150. Inverse non-metricity in f(Q) gravity: cosmology and observational constraints

Simão Marques Nunes (Institute of Astrophysics and Space Sciences (Lisbon Portugal))

10/07/2026 14:10

Talk at the school (week 1)

Student Talks

In this talk I will present a minimal modified gravity model within the symmetric teleparallel formulation, based on an inverse non-metricity term that introduces no additional free parameters with respect to $\Lambda$CDM. I will discuss its main cosmological signatures as well as observational constraints obtained from CMB data alone and in combination with BAO, RSD, SNIa, and DES data,...

146. Revisiting Quadratic Scalar Field (Fuzzy, Wave, Ultralight) Dark Matter in Light of DESI DR2 and Current Cosmological Observations

Hafiz Inam ullah (ESFM - Escuela Superior de Física y Matemáticas - IPN)

10/07/2026 14:20

Talk at the school (week 1)

Student Talks

We study the cosmological phenomenology of quadratic scalar field dark matter (SFDM) using an implementation in the Boltzmann code CLASS, in which dark matter is modeled as a single ultra-light scalar field with potential V (ϕ) = 12 m2ϕ ϕ2 . Adopting a dynamical-systems approach, we analyze the expansion of the homogeneous scalar field together with its linear perturbations, enabling stable...

164. Taming Instabilities in Mass-Varying Neutrino Cosmology

Vitor da Fonseca (Institute of Astrophysics and Space Siences (Lisbon, Portugal))

10/07/2026 14:30

Talk at the school (week 1)

Student Talks

Mass-varying neutrino models with strong scalar couplings are typically affected by late-time perturbative instabilities. In this talk, I present an inverse symmetron-like phase transition in which the neutrino nonrelativistic transition activates the fifth force, while the subsequent dilution of the neutrino density restores the symmetry and suppresses the coupling. This mechanism avoids...

134. On the potential of pseudo-scalar dark energy

Yunzhi Wu (UniTo and INFN)

10/07/2026 14:40

Talk at the school (week 1)

Student Talks

A cosmological pseudo-scalar field provides a compelling realization of dynamical dark energy (DE). If its coupling to photons is non-negligible, the cosmic microwave background acquires a rotation of its polarization plane, known as cosmic birefringence (CB). We present an extended analysis of several pseudo-scalar DE models and derive constraints on the parameters of their potentials by...

130. Constraining DDE Models with AdS-to-dS and Similar Late-Time Transitions

Mine Gökçen (Istanbul Technical University)

10/07/2026 14:50

Talk at the school (week 1)

Student Talks

With the release of DESI DR2, dynamical dark energy (DDE) models gained unprecedented attention as model candidates to release the current cosmological tensions. However, majority do not perform well in relaxing the H0 tension compared to some of the other novel theoretical and phenomenological DE models in the literature, such as the LsCDM model that can be explained by an AdS-to-dS...

168. Understandig the Dark Sector through reconstructions

David A López Magaña (Universidad Nacional Autónoma de México)

10/07/2026 15:00

Talk at the school (week 1)

Student Talks

Within the standard understanding of cosmology, the existence of Dark Matter and Dark Energy is considered. Together, these constitute approximately 95% of the Universe; however, their behavior is not fully understood. Through reconstructions, the phenomenological behavior of both Dark Energy and Dark Matter can be inferred from astronomical observations. This work addresses the interpolation...

173. Reconstructing dark energy with fewer assumptions

Daniel Kessler (University of Sheffield)

10/07/2026 15:10

Talk at the school (week 1)

Student Talks

We perform minimalistic reconstructions of the dark energy density and equation of state using late-time distance measurements. Our methodology avoids assumptions that correlate the values of these functions over time and instead yields their approximate average evolution within seven redshift bins from z=0 to z=4.2. Constraints are obtained using combinations of baryon acoustic oscillation...

163. Multi-field early dark energy and the Hubble tension

Marco Bella (University of Trento)

10/07/2026 15:20

Talk at the school (week 1)

Student Talks

Early dark energy (EDE) is a popular extension of the $\Lambda$CDM model, which alleviates the Hubble tension by reducing the sound horizon at recombination. The updated Planck high-$\ell$ likelihood (NPIPE), however, places strong constraints on such models.

In this talk, I will present a model with two non-interacting EDE fields active at different redshifts, inspired by the string...

151. Non-linear structure of interacting dark energy model

Yuejia Zhai (University of Sheffield)

10/07/2026 15:30

Talk at the school (week 1)

Student Talks

Following our previous work constraining interacting dark energy (IDE) models, which showed their potential to alleviate the Hubble tension, in this work we investigate the non-linear effects of the IDE scenario favoured by CMB and DESI observations. The implications of IDE for the $S_8$ tension remain unclear, since current weak-lensing and large-scale-structure analyses either exclude highly...

170. Likelihood-Ratio Tests with Correlated Parameter Boundaries: Implications for CMB B-mode Searches

Georgia Kiddier (DAMTP, University of Cambridge)

10/07/2026 16:10

Talk at the school (week 1)

Student Talks

Likelihood-ratio statistics play a central role in assessing detection significance in cosmological analyses. Under regularity conditions, Wilks’ theorem predicts that these statistics follow a $\chi^2$ distribution in the asymptotic limit. When a parameter is restricted to a physical boundary, this result no longer holds, and Chernoff’s theorem provides the corresponding mixed distribution....

166. Cosmic birefringence from a stiff axion-like field

Andrea Minotti

10/07/2026 16:20

Talk at the school (week 1)

Student Talks

When polarized electromagnetic radiation propagates through a region of space permeated by a pseudo-scalar field, the plane of linear polarization undergoes a rotation. The rotation angle depends on the field's values when the radiation is emitted and when it is detected and does not depend on the frequency of the radiation. This phenomenon is called Cosmic Birefringence (CB) and is usually...

140. Cosmic Birefringence and Axion Dark Energy

Lena Stefanie Scheuchl (Max Planck Institute for Astrophysics)

10/07/2026 16:30

Talk at the school (week 1)

Student Talks

Recent analyses of Planck polarization data have reported a hint of cosmic birefringence at the level of a $~3.6\sigma$ deviation from the parity-conserving standard cosmological model. At the same time, tensions between CMB data and large-scale structure observations can be alleviated by replacing the cosmological constant with dynamical dark energy. Ultralight axion-like particles can...

129. CMB spectral distortion anisotropies from photon to dark photon conversions

Sara Evangelista (University of Manchester)

10/07/2026 16:40

Talk at the school (week 1)

Student Talks

Distortions of the CMB power spectrum have been proven to be a powerful probe for several cosmological and astrophysical processes. The energy distribution of the photons could provide complementary information to the well-studied temperature anisotropies, directly accessing pre-recombination physics. Each process releasing energy or changing the photon number density through the history of...

148. Constraining Primordial Magnetic Fields using Rayleigh Scattering of CMB

Kwanit Gangopadhyay (University of Groningen)

10/07/2026 16:50

Talk at the school (week 1)

Student Talks

The presence of magnetic fields has been inferred in extragalactic spaces like voids, and astrophysical mechanisms are unable to explain the magnitude of these fields. This hints towards cosmological magnetic fields of primordial origin, that are amplified by the astrophysical dynamo effect.

As future surveys and telescopes provide higher precision measurements of CMB, LSS and EoR; we are...

175. Exploring the Lyman-Alpha Forest in a Dynamical Dark Energy Cosmology using Cholla

Diego Garza (University of California, Santa Cruz)

10/07/2026 17:00

Talk at the school (week 1)

Student Talks

The Dark Energy Spectroscopic Instrument (DESI) Collaboration, when combining their baryonic acoustic oscillation observations with measurements of supernova surveys and cosmic microwave background data, inference of a best fit cosmology with a time-varying dark energy motivates independent observational tests of a departure from a cosmological constant dark energy. I will discuss the results...

133. Dark energy, spatial curvature, and star formation efficiency from JWST photometric and spectroscopic high-redshift galaxies

Leonardo Comini

10/07/2026 17:10

Talk at the school (week 1)

Student Talks

Early observations from the James Webb Space Telescope (JWST) have revealed an overabundance of massive high-redshift galaxies, raising the question of whether this points to new physics beyond ΛCDM, or an enhanced formation efficiency of massive stars. In this talk, I will present a Bayesian analysis of the most massive galaxies identified in recent JWST photometric and spectroscopic surveys,...

174. Measuring the Expansion Rate of the Universe with Strong Gravitational Lenses

Allan Gabriel Schweinfurth Pupo (Technical University of Munich / Max Planck Institute for Astrophysics)

10/07/2026 17:20

Talk at the school (week 1)

Student Talks

Strong gravitational lensing serves as a powerful, independent probe for measuring the Hubble constant (H0). We present the framework of time-delay cosmography and its relevance to the ongoing Hubble tension. We present the procedure for end-to-end cosmographical analysis. We then present ongoing mass-modelling efforts for two systems: the quadruply lensed quasar J1537-3010 and Supernova Winny...

165. Galaxy clusters as cosmic lenses for high frequency gravitational-waves

Tiziano Zanzarella

10/07/2026 17:30

Talk at the school (week 1)

Student Talks

High-frequency Gravitational Waves~(HFGW) ($f \gtrsim 1$ MHz) offer a distinctive probe of exotic physics and early-Universe cosmology. In the absence of dedicated detectors targeting this frequency range, indirect probes based on graviton–photon conversions in astrophysical magnetic fields become particularly relevant. In this talk we show that the extended magnetic fields permeating Galaxy...

147. Constraining the lensing dispersion from the angular clustering of binary black hole mergers

Fumihiro Chuman (Chiba Universitty)

10/07/2026 17:40

Talk at the school (week 1)

Student Talks

Gravitational waves from inspiraling compact binaries provide direct measurements of luminosity distances and serve as a powerful probe of the high-redshift Universe. In addition to their role as standard sirens, they offer an opportunity to constrain small-scale density fluctuations through the dispersion in the distance-redshift relation induced by gravitational lensing. In this talk, we...

2. Current status of type Ia supernova cosmology

Lluís Galbany (ICE-CSIC)

13/07/2026 09:30

6. The TRGB and JAGB Distance Scales: Current Status, Systematics, and the Hubble Constant

Siyang Li (University of California, Berkeley)

13/07/2026 11:15

The tension between early- and late-universe determinations of the Hubble constant has placed extraordinary demands on the precision and accuracy of the extragalactic distance ladder. I review the current status of two standard candles - the Tip of the Red Giant Branch (TRGB) and the J-region Asymptotic Giant Branch (JAGB) - as independent calibrators of Type Ia supernovae. For each method, I...

1. SH0ES

Adam Riess (online)

13/07/2026 14:00

3. Time-delay cosmography with strongly lensed quasars: current results and future prospects

Martin Millon (University of Geneva)

14/07/2026 09:30

Time-delay cosmography with strongly lensed quasars provides a direct, one-step measurement of the Hubble constant in the local Universe, independent of the cosmic distance ladder and early-Universe probes. By measuring the time delays between multiple images of a variable background quasar, and modeling the gravitational potential of the deflector galaxy, one can infer absolute distances that...

4. Alternative routes to H0: time-delay cosmography with lensed SNe and the tailored expanding photosphere method for SNe II

Stefan Taubenberger

14/07/2026 11:15

In this talk, I will present two indepent local techniques to measure the Hubble constant.
Time-delay cosmography with strongly lensed SNe has first been proposed more than 60 years ago, but has become feasible only very recently with the machine-learning aided compilation of large catalogues of strong lenses and the advent of telescopes/surveys such as Euclid, Rubin LSST, ZTF, and JWST. I...

137. The present and the future of quasars in cosmology

Elisabeta Lusso

14/07/2026 14:00

I will review what the prospects of quasars in the context of observational cosmology are and I will present recent measurements of the expansion rate of the Universe based on a Hubble diagram of quasars detected up to the highest redshift ever observed (z~7.5).
The derived distances are in agreement with the standard flat LCDM model up to redshift of ~1.5, but they show significant...

7. KIDS

Dr Benjamin Stölzner (Ruhr University Bochum)

15/07/2026 09:30

8. DES

Marco Raveri (University of Genova)

15/07/2026 11:15

9. Weak lensing: what's next?

Isaac Tutusaus (ICE/IRAP)

15/07/2026 14:00

Stage-III galaxy surveys have shown that weak lensing, and combined 3x2pt analyses, can provide exquisite constraints on the dark components of the Universe. Following a successful launch in July 2023 and the start of its scientific survey in February 2024, Euclid has become the first stage-IV photometric survey in operations. This marks the start of even more exciting science from weak...

11. LSS beyond the BAO

Marko Simonovic

16/07/2026 09:30

10. Reconstructing the Universe using Peculiar Velocities of Type Ia Supernovae

Francesco Sorrenti (ICC - University of Barcelona)

16/07/2026 11:15

Cosmology is the study of the origin, composition, evolution, and ultimate fate of the Universe. In recent decades, there have been significant advances in both the observational and theoretical aspects of our understanding of the Universe. The study of Type Ia Supernovae (SNe Ia) has been instrumental in driving this progress. Despite these advances, many questions in cosmology remain open....

12. Particle cosmology in the era of tensions

Martina Gerbino (INFN Ferrara)

16/07/2026 14:00

Cosmology is one of the most promising avenues to learn about fundamental properties of the building blocks of the Universe. In particular, new-generation experiments will transform the search for light relics, including neutrinos. In this talk, I will give an overview of where we stand and some thoughts on how to move forward as intriguing discrepancies between standard model predictions,...

13. CMB: a global view

Lloyd Knox

17/07/2026 09:30

14. Dark Energy: what's next?

Guadalupe Cañas-Herrera

17/07/2026 11:15

The nature of dark energy remains one of the most profound open questions in modern cosmology. Despite two decades of increasingly precise observations, the standard cosmological model—anchored by a cosmological constant—continues to provide an excellent phenomenological fit, while raising deep theoretical tensions. As we enter the era of high-precision large-scale structure surveys, led by...

15. Modified recombination meets the Hubble tension

Jens Chluba (JBCA)

17/07/2026 14:00

The recombination history of the universe is one of the crucial theoretical ingredients for the computation of the CMB temperature and polarization power spectra. In this talk, I will discuss this link and show how modified recombination scenarios help alleviate the Hubble tension. Beyond changes to the average recombination history I will also consider transport corrections in the clumpy...

109. Cosmology at the Crossroads: Puzzles and Perspectives

Prof. Ruth Durrer (DPT Université de Genève)

20/07/2026 09:00

Talk at conference (week 3)

Cosmology is arguably the most captivating field in physics today. Its unique appeal lies not only in how it integrates all fields of physics, but also but also in the close relationship between theory and observation. Enormous progress has been made and is still to be expected in cosmological observations. For theorists, the primary challenge remains: how can we best leverage these...

54. Invading Florence with Elephants Across the Phantom Divide

Eric Linder (LBL)

20/07/2026 09:45

Talk at conference (week 3)

Cosmological data indicates that dark energy was phantom (w<-1) above
z=1, rapidly evolved across the phantom divide (w=-1), and today has w>-1.
These properties may arise from different dark components (a chimera) or
have a unified origin (an elephant - a single animal despite scientists
in the dark guessing a snake for the trunk, tree trunks for the legs, etc).
I describe ideas for dark...

128. Time-delay cosmography: present and future

Sherry Suyu (Technical University of Munich / Max Planck Institute for Astrophysics)

20/07/2026 11:00

Talk at conference (week 3)

Strong gravitational lenses with measured time delays between the multiple lensed images provide an effective way to measure the Hubble constant H0, a key cosmological parameter that sets the expansion rate of the Universe. Lensed quasars with exquisite observations have been used to measure H0, providing competitive results. Exciting discoveries of the first strongly lensed supernovae are...

144. The H0 world cup

Nils Schöneberg (LMU Munich)

20/07/2026 11:45

Talk at conference (week 3)

With the Hubble tension recently reaching a level of around $7\sigma$ and supported from various independent directions, now it is more crucial than ever to compare the performance of different mechanisms to ease the Hubble tension. In this talk I present a fair comparison of such models dubbed the $H_0$ world cup, which serves a follow-up to the previous $H_0$ olympics. Improvements include...

89. TBD

Prof. Adam Riess (online)

20/07/2026 14:00

Contributed talks

92. DES results and their cosmological implications

Prof. Sesh Nadathur (TBD)

21/07/2026 09:00

93. Testing LCDM with Large-Scale Structures

Prof. Dragan Huterer

21/07/2026 09:45

61. Combined probes of dark energy in the nonlinear regime

Alkistis Pourtsidou (University of Edinburgh)

21/07/2026 11:00

Talk at conference (week 3)

Over the coming years cosmology will be transformed, with enormous amounts of new data being collected by Stage IV spectroscopic and photometric galaxy surveys: DESI, Euclid, Rubin, and Roman. Most of the high precision data these surveys provide are within the small-scale (nonlinear) regime, which is extremely difficult to model. This includes nonlinear modelling of dark matter and biased...

108. DESI Full-Shape Constraints and the Challenge of Bias Degeneracies

Dr Samuel Brieden (TTK, RWTH Aachen)

21/07/2026 11:45

Talk at conference (week 3)

The Dark Energy Spectroscopic Instrument (DESI) provides highly precise measurements of galaxy clustering. To extract the maximum cosmological information from these datasets, Full-Shape and ShapeFit analyses based on the Effective Field Theory of Large-Scale Structure (EFTofLSS) have become the standard approach. However, marginalizing over a broad parameter space of EFTofLSS nuisance...

114. Cosmology probes of Dark Matter

Laura Lopez Honorez (Université Libre de Bruxelles)

22/07/2026 09:00

Talk at conference (week 3)

In this talk, I will present a review of selected cosmological probes of dark matter, considering both particle candidates and macroscopic objects such as primordial black holes. These probes may test energy injection or the damping of small-scale structures in the early Universe. Whenever possible, I will highlight how these probes and their associated methodologies can be used to tighten...

52. Waving in the Dark: Noisy, Warm, and Spinning Dark Fields

Mustafa Amin (Rice University)

22/07/2026 09:45

Talk at conference (week 3)

When bosonic dark matter is sufficiently light, wave-dynamical effects can manifest on astrophysical and even cosmological scales. I will review a range of such phenomena across both linear and nonlinear regimes, including enhancements and suppressions in the density power spectrum, wave interference, soliton formation, and in some cases, generation of macroscopic spin angular momentum...

190. Unifying Early and Late Dark Energy

Jeremy Sakstein (University of Hawai'i)

22/07/2026 11:00

Talk at conference (week 3)

Unifying Early and Late Dark Energy

62. Constraints on the Injection of Radiation in the Early Universe

Jason Kumar (University of Hawaii)

22/07/2026 11:45

Talk at conference (week 3)

We consider the generic injection of radiation (both dark and electromagnetic) during the epoch between big bang nucleosynthesis (BBN) and recombination. The contribution of the additional radiation to the number of effective neutrinos may be quite small in this scenario, since dark radiation and electromagnetic radiation provide contributions of opposite sign. However, the injection of...

87. Stress-Testing the Universe with CMB Spectral Distortions

Bryce Cyr (brycecyr@mit.edu)

23/07/2026 09:00

Talk at conference (week 3)

TBA

118. Shedding light on the Hubble tension with novel cosmological probes: Cosmic Chronometers and Gravitational Waves

Michele Moresco (University of Bologna)

23/07/2026 09:45

Talk at conference (week 3)

Modern cosmology is entering a critical phase, as increasingly precise measurements from multiple standard probes have unveiled tensions that may hint at new physics. Whether these discrepancies arise from unaccounted systematics or signal a genuine crisis in our understanding of the Universe is still an open question. In this context, it becomes crucial to explore independent and...

110. Standard siren cosmology

Antonella Palmese (Carnegie Mellon University)

23/07/2026 11:00

Talk at conference (week 3)

Thanks to the synergies between gravitational wave (GW) experiments, such as LIGO/Virgo/KAGRA, and electromagnetic observations of transients and galaxies, a variety of novel cosmological measurements has recently become possible. Several of these measurements rely on the use of GW events as "standard sirens”. Following the detection of the first electromagnetic counterpart to a GW event,...

102. TBD

TBD

23/07/2026 11:45

112. Recent progress on cosmic inflation

Dr Matteo Fasiello (IFT Madrid)

24/07/2026 09:00

Talk at conference (week 3)

I will review recent progress on inflation with particular attention to axion-inflation models, their dynamics and gravitational wave/PBH signatures.

111. Cosmological implications of generic features of string compactifications

Michele Cicoli (University of Bologna)

24/07/2026 09:45

Talk at conference (week 3)

I will review the cosmological implications of generic features of string compactifications like the presence of fundamental strings, field-dependent couplings, rolling moduli which are gravitationally coupled, axion-like particles and hidden photons. These implications include inflation, cosmic superstrings and gravity waves, reheating, dark radiation and dark energy.

113. Gravitational waves from Inflation

Ema Dimastrogiovanni (VSI Institute, University of Groningen)

24/07/2026 11:00

Talk at conference (week 3)

Primordial gravitational waves offer a rare opportunity to probe physics at extremely high energies, opening a window onto the very earliest moments of the universe's history. I will discuss how cosmic inflation can lead to new and distinctive gravitational-wave signals within the reach of current and/or near-future interferometers. I will also show how anisotropies in the gravitational-wave...

156. Theories of Large-Scale Structure and Newtonian Motion Gauges

Julien Lesgourgues (RWTH Aachen University)

24/07/2026 11:45

Talk at conference (week 3)

Standard Perturbation Theory, Effective Field Theory and other theories of large-scale structure are usually formulated in terms of Newtonian equations. Newtonian motion gauges were initially designed to enhance Newtonian N-body simulations. They also offer an opportunity to perform SPT or EFTofLSS calculations within a general-relativistic framework. At the same time, they allow to...

64. Constraints on neutrino masses in light of cosmological tensions

Julien Lesgourgues (RWTH Aachen University)

27/07/2026 09:30

Cosmological upper bounds on the summed neutrino mass are in increasing tension with respect to laboratory lower bounds as long as standard neutrino physics and the LambdaCDM cosmological model are assumed. I will stress that the tension is driven by measurements of the Universe expansion rate (from BAO, CMB and supernovae data), completed by information from CMB lensing. I will show that...

65. How to ease the Hubble tension

Nils Schöneberg (LMU Munich)

27/07/2026 11:15

Reducing the sound horizon has been shown to be a very efficient way to reconcile the Hubble tension. In this talk I focus on how and why an increased Hubble parameter can follow from such a reduced sound horizon, and what guardrails the CMB provides in this case. The resulting degeneracies with the other cosmological parameters force models like early dark energy and models that shift the...

66. Reconstructing Inflationary Dynamics Beyond Slow Roll from Cosmological Observables

Dr Rodrigo Calderon (Institute of Physics, Czech Academy of Sciences)

27/07/2026 14:00

Understanding the physics of the early Universe remains one of the central goals of modern cosmology. While the inflationary paradigm provides a compelling mechanism for generating primordial perturbations, most observational constraints to date rely on the slow-roll approximation and specific model assumptions. In this talk, I present a model-agnostic approach to probing inflationary dynamics...

67. Modeling Higher-Order Bias via the Cosmic Web: Implications for DESI Full Shape Analyses

Samuel Brieden (ICC, University of Barcelona)

28/07/2026 09:30

The standard excursion set approach to dark matter halo formation typically evaluates local collapse without explicitly accounting for the cosmic-web geometry of the large-scale structure. In this talk, I will present a theoretical framework for halo and galaxy bias featuring explicit environmental dependence, inspired by the Web-Halo model. By physically conditioning halo collapse on cosmic...

68. Dark Energy after DESI

Eric Linder (LBL)

28/07/2026 11:15

What are the key advances needed in data and in theory to understand dark energy in 2026 and beyond?

69. Model Independent Reconstruction of the Cosmological Evolution at Low Redshifts and Possible Theoretical Explanation

Anjan Ananda Sen (Jamia Millia Islamia Central University)

28/07/2026 14:00

We investigate the late-time expansion history of the Universe using a model-independent reconstruction of
cosmological distances based on the latest DESI-DR2 BAO measurements and the DES Dovekie Type Ia
Supernova compilation. We reconstruct the expansion rate over the full redshift range probed by the data and
compare it with the prediction of the Planck 2018 ΛCDM model. We identify a...

70. Screened Scalar Fields in Cosmology: Theory and Tests

Anne-Christine Davis (University of Cambridge)

29/07/2026 09:30

Scalar-tensor gravity could help resolve some cosmological mysteries. However such theories give rise to fifth forces, which are not observed in solar system tests of gravity. Hence the coupling between the scalar field and matter must either be very small of the fifth force must be screened. The talk will explain the screen8ng of such scalar fields. It will then look at ways of testing such...

72. The influence of small -scale matter fluctuations on the large scale dynamics of light scalars

philippe brax (IPHT Saclay)

29/07/2026 11:15

Dark matter is present from small to large scales. When dark energy couples to matter, one can integrate out the matter distribution on small enough scales and obtain effects on the dynamics of light scalars (dark energy) on large scales. I will introduce the Schwinger-Keldysh formalism to do this properly and deduce some possible unexpected (?) results for dark energy on large scales.

71. Electromagnetically K-mouflaged dark matter

Jose Beltrán Jiménez (Universidad de Salamanca)

29/07/2026 14:00

I will discuss a cosmological scenario where dark matter is provided with a dark electric charge with a dark electromagnetic sector featuring a screening mechanism so that all the effects only appear at low redshift, when dark matter is sufficiently clustered. Within these models, it is natural to have a universe described by a Lemaitre model instead of a FLRW. Instead of solving the full...

73. Interacting dark sectors and axio-dilaton cosmology

Carsten van de Bruck

30/07/2026 09:30

74. Lagrangian models of interacting dark matter and dark energy

Erik Jensko

30/07/2026 11:15

Extensions of LCDM with interactions between dark matter and dark energy are a popular route to address the ongoing cosmic tensions. However, many recent models are phenomenological and do not admit a Lagrangian description, leaving their theoretical validity uncertain. One example is phenomenological dark energy fluid models with a phantom equation of state, where the perturbative structure...

75. Neutrinos, Dark Sectors, and Cosmological Tensions

Sebastian Trojanowski (National Centre for Nuclear Research, Poland & Astrocent, NCAC PAS)

30/07/2026 14:00

While standard LambdaCDM cosmology remains remarkably successful, persistent observational discrepancies suggest the need for physics beyond minimal frameworks. In the talk, we will explore the cosmological implications of deeper, interconnected structures within the dark sector, focusing on new physics interactions between neutrinos, dark matter, and light mediators. We will examine how they...

78. Quantum Field Theory Approach To Gravitational Wave Physics

Gaetano Lambiase

31/07/2026 09:30

We employ the Quantum Field Theory approach to investigate graviton emission from massive sources. Applying this method to gravitational-wave emission by binary systems in fourth-order gravity, we find a cancellation between the contributions of the massless graviton and the additional massive spin-2 ghost and scalar modes. Consequently, the General Relativity quadrupole formula is not...

77. Scalar-tensor theories from a particle's perspective

Sergio Sevillano Muñoz (University of Pennsylvania)

31/07/2026 11:15

Scalar–tensor theories provide a theoretically motivated extension of gravity that includes an additional scalar degree of freedom non‑minimally coupled to the gravitational sector. Their consistency with local tests of gravity is possible mainly due to screening mechanisms, which dynamically suppress scalar interactions in high-density environments. In this talk, I will develop a...

79. Sign-Switching $\Lambda_{\rm s}$CDM: Theoretical Realizations and Implications for Cosmological Tensions

Prof. Özgür Akarsu (Istanbul Technical University)

31/07/2026 14:00

The remarkable phenomenological success of the concordance $\Lambda$CDM model is accompanied by persistent tensions and anomalies, including those associated with $H_0$, $S_8$, the growth index $\gamma$, and cosmological inference of the neutrino-mass sum $\sum m_\nu$. These discrepancies may reflect unaccounted-for systematics, but they may also point to missing structure in the standard...

186. A superposition quantum universe and its perturbations

Lisa Mickel (Institut d'Astrophysique de Paris)

Talk at conference (week 3)

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...

169. AGN Variability in the Survey Era: From Accretion-Disk Physics to Cosmological Distances

Júlia Laguna I Miralles (University of Cambridge)

Talk at conference (week 3)

Large time-domain surveys are turning AGN variability into a population-scale probe of both supermassive black-hole accretion and cosmology. UV/optical variability depends on rest-frame timescale, wavelength, and luminosity: at fixed wavelength and time lag, more luminous sources vary less. This luminosity anti-correlation motivates Type 1 AGN variability as a potential distance indicator...

177. Asymmetric Reheating of Dark QED

Simon Clery (Technical University of Munich (TUM))

Talk at conference (week 3)

The reheating epoch following inflation sets the initial conditions for the subsequent thermal history of the Universe, but remains largely unconstrained prior to Big Bang nucleosynthesis. In many extensions of the Standard Model, the inflaton may decay simultaneously into visible and hidden sectors, leading to non-standard cosmological histories. One possibility is an asymmetric reheating in...

142. BAO Experiments in Tension: Methods, Redshift Coverage, and Interpretation

Ruchika Ruchika (University of Salamanca)

Talk at conference (week 3)

I will talk about systematic differences between 2D and 3D Baryon Acoustic Oscillation (BAO) analyses. While 2D BAO measurements appear to ease the Hubble tension by accommodating both a higher H₀ and a larger sound horizon, they simultaneously introduce tension with Planck constraints on Ωₘh², reflecting systematic shifts relative to 3D analyses.

I then examine the apparent preference for...

181. Beyond LCDM: Dynamical Dark Energy and High-Redshift Reionization

Hanyu Cheng

Talk at conference (week 3)

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

60. Beyond ΛCDM with a Logistic RG-like Flow of the Low Redshift Cosmic Evolution

Prof. Anjan Ananda Sen (Jamia Millis Islamia)

Talk at conference (week 3)

Recent observations hint at possible late-time deviations from ΛCDM. We introduce a minimal phenomenological framework in which the total equation of state wT(z) follows a logistic evolution motivated by renormalization-group–like flow between cosmological fixed points. Using DESI-DR2 BAO, DES supernova data, and CMB distance priors, we find that this parametrization provides an improved...

153. Breaking Galaxy–Halo Degeneracies with Anisotropic Small-Scale Three-Point Clustering

Lado Samushia (Kansas State University)

Talk at conference (week 3)

Small-scale galaxy clustering contains cosmological information that is complementary to standard BAO measurements and potentially highly constraining for tests of structure growth and fundamental physics. Realizing this potential, however, requires a robust treatment of the uncertain connection between galaxies and dark-matter halos. In this talk, I will present two recent studies that...

185. cloe-org: a new computational environment for LSS cosmology

Guadalupe Cañas-Herrera (Leiden Observatory)

Talk at conference (week 3)

The latest generation of large-scale structure surveys requires computational frameworks that are not only accurate, but also modular, reproducible, fast and sustainable in time. We present cloe-org, a new computational environment for LSS cosmology, built around the development of CLOE: the Cosmology Likelihood for Observables in Euclid. Designed to support end-to-end cosmological analyses,...

115. Combined probes of dark energy

Alkistis Pourtsidou (University of Edinburgh)

Talk at conference (week 3)

I will discuss challenges and opportunities for probing dark energy with diverse observational probes, including CMB, galaxy clustering, cosmic shear, and 21cm intensity mapping. I will highlight the role of accurate nonlinear modelling and modern statistical techniques to mitigate various issues in the data analysis. I will present results from re-analysing data from surveys like BOSS, KiDS,...

188. Constraining 2-loop EFTofLSS with weak lensing

DESPOINA FARAKOU (CEICO, FZU)

Talk at conference (week 3)

We present the Sym-EFT emulator [arXiv:2511.05093], which enables fast and accurate predictions for the nonlinear matter power spectrum up to two loops within the Effective Field Theory of Large-Scale Structure (EFTofLSS). We discuss its applications to weak gravitational lensing, including constraints on 2-loop EFTofLSS counterterms from current DES Year 3 cosmic shear and CMB lensing data....

143. Constraining structure growth and primordial non-Gaussianity with Euclid AGNs and CMB lensing

Matteo Peronaci

Talk at conference (week 3)

Measuring the growth of cosmic structure across time is a powerful way to test the standard cosmological model. With the Euclid mission, we are gaining an unprecedentedly large and deep sample of Active Galactic Nuclei (AGN), providing a unique, highly biased tracer of large-scale structure reaching far into the high-redshift universe. In this work, we explore the cosmological potential of...

152. Constraints on cosmology with transverse-velocity and CMB cross-correlations

Yanchuan Cai (University of Edinburgh)

Talk at conference (week 3)

On large scales, peculiar velocities encode a wealth of cosmological information. While line-of-sight components are routinely probed, measuring transverse velocities has remained challenging. I will present a new detection of dipolar patterns associated with transverse velocities, imprinted on the Cosmic Microwave Background through the integrated Sachs–Wolfe effect and gravitational lensing....

96. Constraints on dark matter from cosmology

Prof. Laura Lopez-Honorez

16. Contribution 1

25. Contribution 10

26. Contribution 11

27. Contribution 12

28. Contribution 13

29. Contribution 14

30. Contribution 15

17. Contribution 2

18. Contribution 3

19. Contribution 4

20. Contribution 5

21. Contribution 6

22. Contribution 7

23. Contribution 8

24. Contribution 9

105. Cosmological implications of generic features of string compactifications

Prof. Michele Cicoli

162. Cosmology with the line-of-sight shear of strong gravitational lenses

M. Daniel Johnson (Laboratoire Univers et Particules de Montpellier)

Talk at conference (week 3)

Weak gravitational lensing distorts shapes and brightnesses, introducing correlations in the apparent ellipticities of galaxies, and enabling constraints on cosmological parameters such as Omega_m and sigma_8. Strong gravitational lenses are also subject to weak lensing perturbations, leaving a measurable imprint in the form of line-of-sight (LOS) shear. Stage-IV photometric galaxy surveys are...

88. Cosmology: current status and opening remarks

Prof. Ruth Durrer

Talk at conference (week 3)

53. Coupled Dark Energy and Dark Matter for DESI: An Effective Guide to the Phantom Divide

Stephen King (University of Southampton)

Talk at conference (week 3)

Motivated by the recent Dark Energy Spectroscopic Instrument (DESI) DR2 preference for dynamical dark energy, we study interacting dark energy models in which a canonical quintessence field couples to cold dark matter through a field-dependent mass $m(\phi)$. In such scenarios, the effective equation of state inferred under the assumption of non-interacting dark sectors, $w_{\rm eff}(z)$, can...

31. Dark Energy and Modified Gravity

Alessandra Silvestri

127. Dark Energy and Modified Gravity in the DESI Era: Breaking Degeneracies with Multi-Probe Strategies

Andrea Cozzumbo (GSSI - Gran Sasso Science Institute)

Talk at conference (week 3)

The recent Baryon Acoustic Oscillation measurements from the Dark Energy Spectroscopic Instrument (DESI) reveal persistent tensions in modern cosmology, including hints of dynamical dark energy evolution and neutrino mass constraints so stringent they conflict with oscillation experiments. A fundamental challenge is that theoretically distinct models produce nearly indistinguishable expansion...

178. Deciphering the coupled scalar dark sector.

Saba Rahimy (Swansea University)

Talk at conference (week 3)

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...

182. Defocusing dark energy: Raychaudhuri diagnostics beyond $w<-1/3$ and the phantom divide

Prof. Özgür Akarsu (Istanbul Technical University)

Talk at conference (week 3)

Evolving dark energy is back at the center of cosmology, and several scenarios under active discussion---sign-switching $\Lambda_{\rm s}$CDM, AdS-to-dS transitions, and modified-gravity backgrounds recast in GR like form---feature an effective dark-energy density that is negative in the past and crosses zero at some redshift $z_\dagger$. Our standard language quietly assumes this never...

167. DESI Full-Shape Constraints and the Challenge of Bias Degeneracies

Samuel Brieden (TTK, RWTH Aachen)

Talk at conference (week 3)

The Dark Energy Spectroscopic Instrument (DESI) provides highly precise measurements of galaxy clustering. To extract the maximum cosmological information from these datasets, Full-Shape and ShapeFit analyses based on the Effective Field Theory of Large-Scale Structure (EFTofLSS) have become the standard approach. However, marginalizing over a broad parameter space of EFTofLSS nuisance...

76. Discussion

184. Dynamical dark energy from QCD vacuum

Dong Ha Lee (University of Sheffield)

Talk at conference (week 3)

The nature of dark energy has been a growing point of debate in recent years, particularly after the DESI measurements of the Baryon Acoustic Oscillations. While frequentist metrics appear to indicate a growing preference for a dynamical dark energy, some bayesian approaches indicate otherwise. Beyond this, there also lies the question of whether there exists a physical motivation behind any...

172. EFT-Ramses Effective Field Theory of Dark Energy

Nathaniel Woodcock (Durham University)

Talk at conference (week 3)

While the standard Lambda-CDM model has been an excellent empirical fit since the discovery of cosmic acceleration, theoretical challenges surrounding the cosmological constant (Lambda) have strongly motivated the exploration of alternative MG and dynamical DE frameworks. Investigating the physical nature of this acceleration requires N-body simulations, preparing for the high-precision data...

101. Emerging cosmological probes and their role in unveiling the Universe

Prof. Michele Moresco

157. Evidence of evolving dark energy from a Hubble Diagram of Quasars

Guido Risaliti (Università di Firenze)

Talk at conference (week 3)

I present new cosmological fits to the Hubble diagram built from supernovae and a homogeneous quasar sample spanning a redshift interval z = 0.7--3.5. The quasar distances are derived from the non-linear relation between X-ray and UV luminosities, and the sample is selected to minimize dust reddening, gas obscuration, host-galaxy contamination, and selection biases. This provides high-quality...

171. Exploring the Lyman-Alpha Forest in a Dynamical Dark Energy Cosmology using Cholla

Diego Garza (University of California, Santa Cruz)

Talk at the school (week 1)

The Dark Energy Spectroscopic Instrument (DESI) Collaboration, when combining their baryonic acoustic oscillation observations with measurements of supernova surveys and cosmic microwave background data, inference of a best fit cosmology with a time-varying dark energy motivates independent observational tests of a departure from a cosmological constant dark energy. I will discuss the results...

95. Full-shape / shape-fit analyses from DESI

Dr Samuel Brieden

116. Halo Abundance in Decaying Dark Matter Models

Thomas Montandon (Laboratoire Univers et Particule de Montpellier (LUPM))

Talk at conference (week 3)

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 space...

34. Hands-on 1/Lecture 1

Anna Porredon (CIEMAT)

38. Hands-on 2/Lecture 2

42. Hands-on 3/Lecture 3

46. Hands-on 4/Lecture 4

47. Hands-on 5/Lecture 5

49. Hands-on 6/Lecture 6

99. Injection of radiation in the early Universe and its cosmological implications

Prof. Jason Kumar

91. Invading Florence with Elephants Across the Phantom Divide

Prof. Eric Linder

136. Isocurvature Induced Gravitational Waves at Pulsar Timing Arrays

Peizhi Du (University of Science and Technology of China)

Talk at conference (week 3)

The standard cosmological model (ΛCDM model) assumes adiabatic initial conditions for primordial density perturbations. However, many new physics scenarios can deviate from this assumption and generate isocurvature perturbations across a wide range of scales. In this talk, I will discuss how isocurvature can induce gravitational waves at second order in perturbation theory. Moreover, Pulsar...

155. KiDS-Legacy: Constraints on Horndeski gravity

Dr Benjamin Stölzner (Ruhr University Bochum)

Talk at conference (week 3)

In this talk, I will present constraints on modified gravity using the latest weak lensing data from the Kilo-Degree Survey (KiDS-Legacy), in combination with DESI measurements of baryon acoustic oscillations, eBOSS observations of redshift space distortions, and cosmic microwave background anisotropies from Planck. This analysis explores the Horndeski class of modified gravity models within...

149. Large deviations for halos and voids: beyond perturbative non-gaussianities

Martin Teuscher (LPSC Grenoble, France)

Talk at conference (week 3)

The excursion-set formalism provides a key connection between primordial inflationary fluctuations and the abundance of cosmic structures such as dark matter halos and voids, traditionally assuming Gaussian random walks. In this work, we extend this framework to fluctuations whose distribution presents strongly non-Gaussian tails, beyond the reach of perturbative approaches to primordial...

39. Lecture 1

Alessandra Silvestri (Leiden University), Anna Porredon (CIEMAT), Antonella Palmese (Carnegie Mellon University), Dan Scolnic, Tanvi Karwal, Tristan Smith

Supernova and the cosmic distance ladder

32. Lecture 2

CMB and next-generation surveys

40. Lecture 2

Alessandra Silvestri (Leiden University), Anna Porredon (CIEMAT), Antonella Palmese (Carnegie Mellon University), Dan Scolnic, Tanvi Karwal, Tristan Smith

33. Lecture 3

Large Scale Structure and BAO

41. Lecture 3

35. Lecture 4

Dark Energy and Modified Gravity

43. Lecture 4

36. Lecture 5

Cosmology with Gravitational Waves

44. Lecture 5

37. Lecture 6

Numerical tools and parameter estimation

45. Lecture 6

180. LOS Shear Cosmology - Testing Measurability with Hydrosimulated Strong Gravitational Lenses

Giacomo Queirolo

Talk at conference (week 3)

Strong gravitational lensing is an increasingly powerful tool for cosmological studies. In particular, the weak-lensing shear induced by large-scale structures along the line of sight (LOS) of a strong lens can itself be treated as an observable, carrying information about the matter distribution in the Universe and thus representing a valuable cosmological probe.

While the theoretical...

160. Measuring the evolution of the Weyl potential

Isaac Tutusaus (ICE/IEEC/IRAP)

Talk at conference (week 3)

The Weyl potential, which is the sum of the spatial and temporal distortions of the Universe's geometry, provides a direct way of testing the theory of gravity and the validity of LCDM. In this talk I will first present a methodology to directly measure the evolution of this potential from galaxy-galaxy lensing measurements with a minimum amount of assumptions. I will then show the results...

123. Mimicking Phantom Dark Energy with Evolving Dark Matter Mass

ALESSIO NOTARI (Universita di Roma Sapienza)

Talk at conference (week 3)

I will present a framework to reproduce any cosmological background via energy exchange between dark energy and dark matter, where a quintessence field controls the DM mass. This setup achieves a phantom-crossing background without introducing ghosts. As a proof of concept, I will reproduce the background that best fits the recent DESI+CMB+DESY5 data. While the background expansion is...

94. Multimessenger large-scale structure

Prof. Alkistis Pourtsidou

158. Non-linear effects of interacting dark energy model

Yuejia Zhai (University of Sheffield)

Talk at conference (week 3)

Following our previous work constraining interacting dark energy (IDE) models, which showed their potential to alleviate the Hubble tension, in this work we investigate the non-linear effects of the IDE scenario favoured by CMB and DESI observations. The implications of IDE for the $S_8$ tension remain unclear, since current weak-lensing and large-scale-structure analyses either exclude highly...

161. Particle cosmology in the era of tensions

Martina Gerbino (INFN Ferrara)

Talk at conference (week 3)

Cosmology is one of the most promising avenues to learn about fundamental properties of the building blocks of the Universe. In particular, new-generation experiments will transform the search for light relics, including neutrinos. In this talk, I will give an overview of where we stand and some thoughts on how to move forward as intriguing discrepancies between standard model predictions,...

107. Primordial gravitational waves as probes of inflationary particle physics

Prof. Ema Dimastrogiovanni

5. QSO cosmology

Matilde Signorini

117. Quantifying Anisotropies in the Local Expansion Rate with Cosmic-Flows 4

Jessica Santiago (Aix Marseille University)

Talk at conference (week 3)

The Cosmological Principle predicts that, on sufficiently large scales, cosmic expansion should appear statistically isotropic to all observers. Testing the limitations of this prediction in the local Universe is, therefore, a first step into properly considering the impacts of local large-scale anisotropies in data analysis and interpretation. In this work, we use the Cosmicflows-4 distance...

104. Recent progress on inflation

Prof. Matteo Fasiello

85. Reframing the Hubble Tension Through the Sound Horizon

Helena García Escudero (Univesity of Southern California)

Talk at conference (week 3)

One of the most striking open problems in modern cosmology is the Hubble tension: the persistent disagreement between measurements of the present-day expansion rate of the Universe obtained from local observations and the lower values inferred from cosmic microwave background data within the standard ΛCDM framework. This mismatch has motivated extensive scrutiny of both late-time measurements...

100. Spectral distortions: early-Universe physics and cosmic tensions

Dr Bryce Cyr

103. Standard siren cosmology

Prof. Antonella Palmese

48. Student Talks 1

50. Student Talks 2

106. TBD

Prof. Julien Lesgourgues

138. TBD

TBD

189. The Universal Rotation Curve of disk galaxies: probing dark matter and the local expansion rate

Tiziano Schiavone (SISSA, Trieste)

Talk at conference (week 3)

The Universal Rotation Curve provides a powerful empirical framework to investigate the distribution of luminous and dark matter in disk galaxies. By adopting normalized radial and velocity coordinates, we investigate the emergence of universal kinematic properties across galaxies with different masses and luminosities. The resulting co-added rotation curves will be analyzed through different...

90. Time-delay cosmography

Prof. Sherry Suyu

179. Time-domain axion searches with magnetic white dwarfs

Hong-Yi Zhang

Talk at conference (week 3)

Magnetic white dwarfs can convert photons into axions in their strong magnetic fields, with the conversion probability modulating the light curve as the star rotates. However, this observable is degenerate with intrinsic stellar variability if the background is modeled too simplistically. We develop a controlled background-degeneracy framework that computes the axion-induced modulation from...

98. Unified models of early and late dark energy

Prof. Jeremy Sakstein

63. Unveiling the Dark Universe with the Sun

Prof. Anne Davis (University of Cambridge)

Talk at conference (week 3)

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

97. Waving in the Dark: Noisy, Warm, and Spinning Dark Fields

Prof. Mustafa Amin

When bosonic dark matter is sufficiently light, wave-dynamical effects can manifest on astrophysical and even cosmological scales. I will review a range of such phenomena across both linear and nonlinear regimes, including enhancements and suppressions in the density power spectrum, wave interference, soliton formation, and in some cases, generation of macroscopic spin angular momentum...