Conveners
Invited: Changbom Park - "No Evidence for a Phantom-Divide-Crossing Dark Energy"
- Chair: Mohammad Ali Gorji
Invited: Takahiro Matsubara - "Tensor Fields and Integrated Perturbation Theory"
- Chair: Swagat Mishra
Invited: Nils A. Nilsson - "Testing spacetime symmetries with current and future gravitational-wave observations"
- Chair: Swagat Mishra
Invited: Teruaki Suyama - "Graviton Floor"
- Chair: Hyunbae Park
Invited: Donghui Jeong - "PowerFull: Modeling wide-angle relativistic power spectrum with the TAM formalism"
- Chair: Hyunbae Park
Invited: Mairi Sakellariadou - "Cosmological and High Energy Physics implications from gravitational-wave background searches in LIGO-Virgo-KAGRA's O1-O4a runs"
- Chair: Shinji Mukohyama
Invited: Ana Achucarro - "Ultra-slow-turn inflation"
- Chair: Yusuke Yamada
Invited: Jaume Garriga - "Primordial black holes and baby universes from ultra-slow roll"
- Chair: Yusuke Yamada
Invited: Misao Sasaki - "Primordial Black Holes and Induced Gravitational Waves"
- Chair: Yusuke Yamada
Invited: Sabir Ramazanov - "Cosmic domain walls: theory and lattice observations"
- Chair: Antonio De Felice
Invited: Gianmassimo Tasinato - " Gravitational Waves Probes of Fundamental Physics: Theory Perspective"
- Chair: Antonio De Felice
Invited: Seong Chan Park - "Superheavy Dark Matter: theory and experiment"
- Chair: Dong-Won Jung
Invited: Alexander Vikman - "Stable Quantum Ghost"
- Chair: Dong-Won Jung
Invited: Antonio De Felice - "Dark Energy in Light of Current Observations and Modified Gravity"
- Chair: Sebastian Bahamonde
Invited: Tsutomu Kobayashi - "Spinoptics in the presence of axion-like particles in curved spacetime"
- Chair: Sebastian Bahamonde
Invited: Shinji Mukohyama - "Emergent time and big-bang"
- Chair: Mohammad Ali Gorji
Invited: Matteo Magi - "Poincaré Gauge Gravity with Extra Massive Spin-2 in Cosmology"
- Chair: Nils Albin Nilsson
Invited: Viatcheslav Mukhanov - "Regularized Quantum Instantons"
- Chair: Sebastian Bahamonde
Invited: Fawad Hassan - "Ghost-free theories of multiple spin 2 fields: bimetric and multimetric interactions"
- Chair: Nils Albin Nilsson
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27/04/2026, 09:20
We apply an extended Alcock–Paczyński (AP) test to the SDSS data to constrain the dark energy equation of state with the Chevallier–Polarski–Linder (CPL) parametrization. The extended AP test method uses the full shape of redshift-space two-point correlation funcion(CF) as the standard shape in order to measure the expansion history of the universe. We calibrate the standard shape by using...
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27/04/2026, 10:50
I will discuss a general framework for correlation analyses of cosmic structures based on nonlinear perturbation theory. In particular, I will outline a new methodology for studying the spatial correlations of astronomical objects described by general tensor quantities, including scalars, vectors and higher-order tensors. The method is based on irreducible representations of the two- and...
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27/04/2026, 11:50
Gravitational waves are now standard tools in modern cosmology, including as probes of fundamental physics. In this talk, I will describe recent results in the efforts to test the symmetries of general relativity using gravitational-waves. Motivated by quantum-gravity phenomenology, I will describe the effective-field theory approach to breaking symmetries and how they can be tested, and I...
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27/04/2026, 14:00
It has been observed that the Universe is permeated by the cosmic photon background, ranging from radio waves to gamma rays. We investigate the conversion of the photon background into gravitons in the presence of background magnetic fields in blazar jets. This graviton background constitutes a graviton floor for high-frequency gravitational wave detectors searching for new physics, analogous...
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27/04/2026, 15:00
The upcoming generation of wide and deep galaxy surveys, such as SPHEREx and Euclid, will provide a unique opportunity to probe the ultra-large scales of structure formation, where primordial non-Gaussianity, often parameterized by fNL, is expected to leave its most detectable imprint. At the same time, these surveys inevitably enter regimes where relativistic and wide-angle effects become...
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28/04/2026, 09:00
I will summarise the most recent LVK results searching for a gravitational-wave background of cosmological origin.
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28/04/2026, 10:30
Multifield inflation models involving ultra-light fields such as moduli and axions are a generic outcome of string and supergravity cosmology. In this talk we consider under what conditions their primordial perturbation spectra may be consistent with observations on the largest (CMB) scales. The usual route is to stabilise the light fields so as to recover single-field inflation. Another...
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28/04/2026, 11:30
A number of inflationary scenarios seeding PBH from adiabatic perturbations also lead to the production of localized eternally inflating relics, which in turn also lead to the formation of PBH once the ambient universe thermalizes. Here, we compare the relative contribution from both channels, focusing on the case of a transient ultra-slow roll (USR) phase followed by a sharp transition to...
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29/04/2026, 09:00
Primordial Black Holes (PBHs) have become one of the most exciting
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topics in cosmology.
They are presumably formed from rare, large curvature perturbations on
scales that can't be accessed by CMB and large scale structure
observations.
If PBHs exist, they will lead to many interesting observational phenomena.
Among them are the induced gravitational waves (IGWs) that may be
detectable... -
29/04/2026, 10:30
I will report results of lattice simulations for cosmic domain walls. The main focus will be on the spectra of gravitational waves produced by these topological defects. There are various types of spectra to be discussed, which originate from different types of domain walls: long-living domain walls, annihilating ones, as well as melting walls characterized by a time-dependent tension. On the...
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29/04/2026, 11:30
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30/04/2026, 10:30
I will discuss the current status of dark matter physics and suggest new territory of superheavy regime.
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30/04/2026, 11:30
I will discuss stable systems with ghosts and how they can even become more stable upon quantization. This stability is due to the existence of a positive definite integral of motion. I will show how to canonically quantize a classically stable system of a harmonic oscillator polynomially coupled to a ghost with an unbounded-below kinetic energy. I will prove that i) the integral of motion has...
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01/05/2026, 10:30
Current cosmological observations have established the accelerated expansion of the Universe, yet the physical nature of dark energy remains elusive. We summarize the current status of cosmology as inferred from observational data and discuss the implications for the nature of dark energy. We review the main observational probes, highlight existing tensions between datasets within the standard...
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01/05/2026, 11:30
We study the propagation of high-frequency electromagnetic waves in curved spacetime in the presence of axion-like scalar fields. We employ the spinoptics approximation and extend the covariant effective action approach recently developed by Frolov to incorporate axion–photon coupling. The resulting spinoptics equations are solved in the background of a Schwarzschild black hole dressed with an...
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01/05/2026, 15:10
We proposes a new avenue for understanding the cosmological singularity. The standard cosmological model contains a generic initial singularity usually referred to as the big bang. Herein, we present a novel idea to extend the description of our Universe beyond this limit. The proposal relies on rewriting physics in a purely Riemannian, i.e. locally Euclidean, 4-dimensional space and the...
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