Thermal Friction in Cosmology

Thermal Friction in Cosmology
Kim Berghaus, Stony Brook
Picturer of Kim Berghaus
Date and time: Tue, Nov 02, 2021 - 2:30pm
Location: LGRT 1033
Category: ACFI Seminar

Rolling scalar fields can play an important role in understanding varying cosmological epochs in a particle physics context. In the usual scenarios the dynamics of the scalar field is dominated by Hubble friction. Coupling the scalar field to light degrees of freedom can give rise to thermal friction which extracts energy from the scalar field into sourcing a thermal bath. If this process is efficient in the early universe, thermal friction acting upon the inflaton scalar field induces a so-called ‘warm inflation’ scenario with unique predictions for observables. However, constructing a robust model with efficient thermal friction is challenging. In this talk, I will illuminate why the axion coupling to a non-Abelian gauge group is the ideal candidate to overcome these challenges by exploiting non-perturbative sphaleron processes. I will also discuss model-building upsides as well as novel observational signatures when applying thermal friction to scalar field solutions of the Hubble tension.