Oscillation in power spectrum of primordial gravitational wave as a signature of higher-order stringy corrections

TL;DR

This paper investigates how higher-order stringy corrections, specifically dilaton oscillations coupled with Gauss-Bonnet terms, can induce distinctive oscillations in the primordial gravitational wave spectrum, potentially observable in CMB B-mode polarization.

Contribution

It demonstrates that dilaton oscillations in string theory can produce unique features in gravitational wave spectra, offering a new observational signature of stringy effects during inflation.

Findings

Oscillations in gravitational wave spectrum due to dilaton dynamics.

Potential imprint of string corrections on CMB B-mode polarization.

Timing of dilaton oscillations affects the spectrum features.

Abstract

In low-energy effective string theory, $\alpha'$ corrections involve the coupling of the dilaton field to Gauss-Bonnet term. We assume that the dilaton potential is fine tuned so that the dilaton field may oscillate rapidly for a while around the minimum of its potential but the inflation background is not affected. By numerical method, we find that if the dilaton starts to oscillate at the time of about $\sim 60$ e-folds before the end of inflation, $\alpha^\prime$ correction may bring unusual oscillations to the inflationary gravitational wave spectrum, which might be measurably imprinted in the CMB B-mode polarization.