Résumé / Abstract Seminaire_GReCO

Séminaire / Seminar GReCO

« Coarse-graining inflation in time: How to make sure you always win the cosmic lottery. »

Ashley Wilkins
School of Mathematics Statistics and Physics, Newcastle University (Newcastle, Royaume-Uni)

The study of stochastic processes is usually plagued by a fundamental problem: the importance of extremely rare events. From barrier escape to the production of primordial black holes, the consequences of extremely rare events can be profound. Which day has a bigger impact on your life; a typical day or the one you won the lottery? In this talk I outline how Functional Renormalisation Group (FRG) techniques can be used to coarse-grain stochastic dynamics in time. This coarse-graining incorporates the impact of the frequent and mundane events as well as the extraordinarly rare. In particular we use the FRG to derive Effective Equations of Motion (EEOM) for the evolution of a spectator field during inflation. We use this to examine the behaviour of the primodial power spectrum in the curvaton scenario. We also apply these EEOM to the first-passage time (FPT) problem to compute the time taken to traverse between two field values and predict the correct exponential tail. Extending this analysis to the inflaton, where these tails correspond to the large production of primordial black holes, is an exciting next step for this research. Based on 2102.04899 and 2211.09649.
mardi 10 janvier 2023 - 14:00
Amphithéâtre Henri Mineur
Institut d'Astrophysique de Paris
Pages web du séminaire / Seminar's webpage