BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Towards reconciling Cosmology\, GR and QFT through non-perturbativ
 e Stochastic Inflation - Yoann Launay\, DAMTP\, University of Cambridge
DTSTART:20240202T130000Z
DTEND:20240202T140000Z
UID:TALK211726@talks.cam.ac.uk
CONTACT:Xi Tong
DESCRIPTION:In the context of inflation\, we show how to account for quant
 um modes in general and numerical relativity on scales bigger than the Hub
 ble radius\, from where they behave classically and can grow non-perturbat
 ively.\n\nWe provide a formulation of Stochastic Inflation in full general
  relativity that goes beyond the slow-roll and separate universe approxima
 tions. Starting from the initial conditions problem in numerical relativit
 y\, we show how gauge invariant Langevin source terms can be obtained for 
 the complete set of Einstein equations in their ADM formulation by providi
 ng a recipe for coarse-graining the spacetime in any small gauge. These st
 ochastic source terms are defined in terms of the only dynamical scalar de
 gree of freedom in single-field inflation and all depend simply on the fir
 st two time derivatives of the coarse-graining window function\, on the ga
 uge-invariant mode functions that satisfy the Mukhanov-Sasaki evolution eq
 uation\, and on the slow-roll parameters.\n\nWe validate the efficacy of t
 hese Langevin dynamics directly using an example in uniform field gauge\, 
 obtaining the stochastic e-fold number without the need for a first-passag
 e-time analysis. As well as investigating the most commonly used gauges in
  cosmological perturbation theory\, we also derive stochastic source terms
  for the coarse-grained first-order BSSN formulation of Einstein's equatio
 ns\, which enables a well-posed implementation for 3+1 numerical relativit
 y simulations.\n\nBased on https://arxiv.org/abs/2401.08530v1
LOCATION:Potter room/Zoom
END:VEVENT
END:VCALENDAR