Gravitational waves in non-singular string cosmologies

TL;DR

This paper investigates how higher-derivative and loop corrections in non-singular string cosmologies influence the evolution of gravitational waves and their resulting spectra, combining analytical and numerical methods.

Contribution

It introduces a detailed analysis of tensor fluctuations in non-singular string models with higher-order corrections, enhancing understanding of gravitational wave spectra in these scenarios.

Findings

Higher-derivative corrections significantly modify the graviton spectrum.

Analytical and numerical results show consistent effects of loop corrections.

Non-singular models produce distinct gravitational wave signatures.

Abstract

We study the evolution of tensor metric fluctuations in a class of non-singular models based on the string effective action, by including in the perturbation equation the higher-derivative and loop corrections needed to regularise the background solutions. We discuss the effects of such higher-order corrections on the final graviton spectrum, and we compare the results of analytical and numerical computations.