Towards the bounce inflationary gravitational wave

TL;DR

This paper analytically derives the primordial gravitational wave spectrum in bounce inflation models, revealing a large-scale cutoff and oscillations that encode bounce physics from about 60 efolds before inflation.

Contribution

It provides a universal analytical calculation of the GW spectrum in bounce inflation, including bounce phase effects, which was not previously established.

Findings

The spectrum has a large-scale cutoff.

Oscillations around the cutoff are significant.

Large-scale GWs encode bounce physics.

Abstract

In bounce inflation scenario, the inflation is singularity-free, while the advantages of inflation are reserved. We analytically calculate the power spectrum of its primordial gravitational waves (GWs), and show a universal result including the physics of the bounce phase. The spectrum acquires a cutoff at large scale, while the oscillation around the cutoff scale is quite drastic, which is determined by the details of bounce. Our work highlights that the primordial GWs at large scale may encode the physics of the bounce ever happened at about $\sim 60$ efolds before inflation.