Field-space surprises in multi-field preheating

by Dr Evangelos Sfatianakis (Institute for High Energy Physics of Barcelona)

Monday 28 Jun 2021, 15:00 → 17:00 Asia/Shanghai

East wing of Pao Yue-Kong Library/2nd-200 - 200# Meeting Room (Tsung-Dao Lee Institute (East wing of Pao Yue-Kong Library))

Abstract

I will discuss preheating in multi-field models of inflation with a curved fieldspace manifold, focusing on two well-studied families of models.

The first includes Higgs inflation and models where the fields couple nonminimally to gravity. I will describe both analytical progress as well as recent lattice simulations that have been used to capture significant nonlinear effects like backreaction and rescattering. I will show how we can we extract the effective equation of state and typical time-scales for the onset of thermalization, quantities that could affect the usual mapping between predictions for primordial perturbation spectra and measurements of anisotropies in the cosmic microwave background radiation. For large values of the nonminimal coupling constants, efficient particle production gives rise to nearly instantaneous preheating.

In the case of two-field generalizations of αα-attractor models with a highly curved hyperbolic field-space manifold, analytical progress can be made for preheating using the WKB approximation and Floquet analysis. I will show the emergence of a simple scaling behavior of the Floquet exponents for large values of the field-space curvature, that enables a quick estimation of the reheating efficiency for any large value of the field-space curvature. In this regime one can observe and explain universal preheating features that arise for different values of the potential steepness. For highly curved field-space manifolds preheating is essentially instantaneous

Biography

I graduated from the School of Electrical and Computer Engineering in Athens, Greece before moving to MIT for my PhD. I received my PhD in 2014 with Alan Guth and David Kaiser working on inflation.

I was a Fortner postdoctoral fellow at the University of Illinois at UrbanaChampaign (2014-1017). After that, I held a joint postdoctoral position between Nikhef (Amsterdam) and Leiden University, in the Netherlands. Since September 2020, I am a "La Caixa" Junior Leader Fellow at the Institute for High Energy Physics of Barcelona, where I'm leading my own group.

Tencent (VooV) Meeting Link: https://meeting.tencent.com/s/rt1F0AZ0zez0

Meeting ID: 913 764 805

Password: 123456

Video review：https://vshare.sjtu.edu.cn/open/f20b99be4c83d988e660bf919f0224da

Sfakianakis_Shanghai_2021.pdf