Secondary Gravitational Waves in Non-local Starobinsky inflation

TL;DR

This paper explores how infinite derivative modifications of gravity influence the gravitational wave background from the early universe, predicting unique blue-tilted spectra that could be tested with future interferometers.

Contribution

It demonstrates the impact of ghost-free infinite derivative gravity on gravitational wave spectra, introducing a new way to test quantum gravity theories.

Findings

Enhanced scalar perturbation power spectrum during inflation

Prediction of blue-tilted gravitational wave spectra

Potential for testing infinite derivative gravity with future detectors

Abstract

We show how infinite derivative modifications of gravity impact on the stochastic background of Gravitational Waves from early Universe. The generic property of the ghost-free theory fixed on Minkowski space-time is the emergence of an infinite number of complex mass states when other classical backgrounds are considered. These additional states are shown to enhance the power spectrum of scalar perturbations generated during inflation. Current and future space-based and terrestrial interferometers offer indirect testing methods for the infinite derivative gravity action, enabling the exploration of new parameter spaces. In particular, we identify unconventional blue-tilted Gravitational Wave spectra, presenting a novel approach for testing infinite derivative quantum gravity in the future.