Cosmology and particle physics seminar
16.02.2026 – 31.12.2026
Organisé par
Faculté des sciencesDépartement de physique théorique
entrée libre
Classement
Catégorie: Séminaire
Sous-événements
Non-minimal coupling and the H0 and BAO tensions
20.02.2026 11:50 – 12:50
The Hubble tension is one of the central topics of cosmology, possibly pointing to new physics beyond LambdaCDM. Furthermore, recent baryon acoustic oscillation (BAO), combined with type Ia supernova, observation unveils a new “tension” indicating possible gaps in our understanding of the recent expansion history of our Universe. One way of explaining the Hubble tension is to introduce new physics in the early Universe during recombination while the BAO “tension” might be explained by evolving dark energy in the late Universe. I will present recent works that study the origin of the cosmological tensions by assuming either early- or late-Universe modification. Based on such analysis, I will discuss how a non-minimally coupled scalar field theory, dubbed thawing gravity, can unify the early- and late-Universe modifications and explain the cosmological tensions.
De Sitter momentum space
06.03.2026 11:50 – 12:50
Quantum field theory in de Sitter space is notoriously difficult. In this talk, I will introduce a new momentum space adapted to de Sitter isometries that provides a natural language and allows us to bypass several difficulties usually encountered. This construction is based on diagonalizing the Casimir operator together with spatial translations, effectively trading the usual (d+1)-dimensional Fourier space for what we call the Kontorovich–Lebedev–Fourier (KLF) space. I will show practical advantages of this description: the quadratic dynamics provides a simple propagator analogous to flat space, and nested time integrals appearing in the computation of cosmological correlators turn into frequency-space integrals over meromorphic functions. I will also show how this construction naturally accommodates the contributions from principal and complementary series in the Källén-Lehmann spectral decomposition of composite operators.
haut