Relic gravitons from non-singular string cosmologies

TL;DR

This paper investigates the generation of relic gravitons in non-singular string cosmologies, proposing a modified evolution equation for tensor perturbations that accounts for higher-order corrections, and analyzing the resulting high-frequency graviton spectrum.

Contribution

It introduces a modified tensor perturbation equation incorporating higher-order corrections to model non-singular string cosmologies.

Findings

Derived a regularized evolution equation for tensor perturbations.

Analyzed the high-frequency spectrum of primordial gravitons.

Provided insights into gravitational wave signatures from string cosmology.

Abstract

In the context of the pre-Big Bang scenario of string cosmology, we propose a modified equation for the evolution of the tensor perturbations, which includes the full contribution of possible higher-order curvature and coupling corrections required to regularise the background evolution. We then discuss the high-frequency branch of the spectrum of primordial gravitons.