2026
6/11
OPEN
Date
2026/6/11（Thu）14:00 〜15:00
Venue
Remote(zoom)
Speaker
Francescopaolo Lopez (SISSA)
Language
English
Contact
Yuko Urakawa/yukour-AT-post.kek.jp
Abstract
Primordial perturbations are born as quantum fluctuations during inflation and are believed to be the seeds of the (classical) cosmic structure observed today, such as the anisotropies in the cosmic microwave background (CMB). In order to shed light on the quantum-to-classical transition of primordial perturbations during single field inflation, we investigate the decoherence of superhorizon scalar curvature perturbations. These are considered as an open quantum system interacting with a time-dependent environment of deep subhorizon tensorial modes through the trilinear interactions predicted by General Relativity. We show that derivativeless interactions provide the dominant contribution to decoherence, while derivative interactions introduce significant non-Markovian effects that tend to slow it down. We introduce a modification to the quantum master equation to take into account the time dependence of the subhorizon environment induced by a time dependent environment of deep subhorizon tensorial modes. Finally, we compute the associated quantum corrections, due to the trilinear interactions, to cosmological correlators. We find a non-perturbative resummation of the quantum corrections to the power spectrum, and we extend this result to the bispectrum, where an analogous resummation structure emerges.
We then follow the evolution of primordial perturbations beyond inflation into the reheating era. Very little is known about this effectively matter dominated phase: it is only constrained to end before Big Bang Nucleosynthesis, at a temperature higher than O(1) MeV. We show that reheating can be long enough that structures, such as halos, can form, inflaton stars can condense inside the halos and eventually grow to collapse into PBH. By employing PBH constraints we are able to improve constraints on reheating temperature, depending on the scale of inflation, strengthening existing bounds by several orders of magnitude.