Damping of tensor modes in inflation

TL;DR

This paper examines how anisotropic stress can damp tensor modes during inflation, finding negligible effects in standard models but potentially significant damping in models with abundant free-streaming particles.

Contribution

It introduces the impact of anisotropic stress on tensor mode damping, highlighting conditions where the effect becomes substantial.

Findings

Negligible damping in standard inflation.

Potentially large damping with free-streaming particles.

Implications for gravitational wave signals.

Abstract

We discuss the damping of tensor modes due to anisotropic stress in inflation. The effect is negligible in standard inflation and may be significantly large in inflation models that involve drastic production of free-streaming particles.