$e^+e^-$ annihilation on the stochastic background of primordial gravitational waves with BKP18

TL;DR

This paper examines how electron-positron annihilation affects the spectrum of primordial gravitational waves from inflation, showing a significant amplitude correction but still below current detection capabilities.

Contribution

It introduces the impact of $e^+e^-$ annihilation on inflationary gravitational wave spectra within $ ext{α}$-attractor models, aligning with recent observational data.

Findings

$e^+e^-$ annihilation causes ~10% amplitude correction.

Energy densities remain within BBN bounds.

Spectra are below current and future detector sensitivities.

Abstract

The evolution of inflationary primordial gravitational waves with the expansion of the universe is studied while taking into account the $e^+e^-$ annihilation which leads to step correction in the spectrum of primordial gravitational waves which is $\sim 10\%$ in the amplitude and $\sim 25\%$ in the energy density. The amplitudes and energy densities are studied for the $\alpha$-attractor inflation models which are in agreement with the recent BICEP/Keck and Planck 2018 joint result. The energy densities are well within the big bang nucleosynthesis bound, but the spectra for these models are very much below the detection range of the currently operating and upcoming detectors.