The Gravitational Wave Spectrum from Cosmological B-L Breaking

TL;DR

This paper predicts a distinctive gravitational wave spectrum from cosmological B-L breaking, involving inflation, preheating, and cosmic strings, which upcoming detectors could observe to test early universe models.

Contribution

It provides a comprehensive calculation of the gravitational wave spectrum from B-L breaking, including inflation, preheating, and cosmic strings, with predictions for future detector sensitivities.

Findings

Gravitational wave spectrum features from B-L breaking are characterized.

Predicted amplitudes exceed inflation-only models, reaching ^{-8}.

Upcoming detectors can test these predictions.

Abstract

Cosmological B-L breaking is a natural and testable mechanism to generate the initial conditions of the hot early universe. If B-L is broken at the grand unification scale, the false vacuum phase drives hybrid inflation, ending in tachyonic preheating. The decays of heavy B-L Higgs bosons and heavy neutrinos generate entropy, baryon asymmetry and dark matter and also control the reheating temperature. The different phases in the transition from inflation to the radiation dominated phase produce a characteristic spectrum of gravitational waves. We calculate the complete gravitational wave spectrum due to inflation, preheating and cosmic strings, which turns out to have several features. The production of gravitational waves from cosmic strings has large uncertainties, with lower and upper bounds provided by Abelian Higgs strings and Nambu-Goto strings, implying \Omega_GW h^2 ~ 10^{-13} - 10^{-8}, much larger than the spectral amplitude predicted by inflation. Forthcoming gravitational wave detectors such as eLISA, advanced LIGO, ET, and BBO/DECIGO will reach the sensitivity needed to test the predictions from cosmological B-L breaking.