Quantum Effects during Inflation

TL;DR

This paper explores how spacetime expansion during inflation affects quantum effects, especially for massless particles, by examining their prolonged virtual existence and related phenomena.

Contribution

It demonstrates the impact of inflation on quantum effects for massless, non-conformally invariant particles, focusing on fermions coupled to scalars, and reviews recent related studies.

Findings

Expansion prolongs virtual particle lifetimes during inflation.

Massless, non-conformally invariant particles exhibit significant quantum effects.

Review of recent studies on quantum phenomena in expanding spacetime.

Abstract

The expansion of spacetime alters the energy-time uncertainty principle, allowing virtual particles to persist longer than in flat space. For a given expansion the effect is largest for massless particles which are not conformally invariant. For a given particle type the effect is largest for inflation. I exhibit these two principles in the context of massless fermions which are Yukawa-coupled to massless scalars. I also review the many related examples which have been studied recently.