Gravitational waves generated by second order effects during inflation

TL;DR

This paper investigates the generation of gravitational waves during inflation caused by second order effects, comparing different theoretical approaches and applying them to slow-roll inflation models.

Contribution

It introduces and compares covariant and metric-based methods for analyzing second order gravitational wave generation during inflation.

Findings

Both methods yield consistent results for gravitational wave perturbations.

Application to slow-roll inflation demonstrates the relevance of second order effects.

The analysis enhances understanding of non-linear contributions to primordial gravitational waves.

Abstract

The generation of gravitational waves during inflation due to the non-linear coupling of scalar and tensor modes is discussed. Two methods describing gravitational wave perturbations are used and compared: a covariant and local approach, as well as a metric-based analysis based on the Bardeen formalism. An application to slow-roll inflation is also described.