Probing the scale of grand unification with gravitational waves

TL;DR

This paper explores how gravitational waves from cosmic strings, resulting from B-L symmetry breaking at grand unification scales, can be detected by LIGO, providing insights into fundamental particle physics and cosmology.

Contribution

It demonstrates that gravitational waves from metastable cosmic strings can serve as probes for the scale of B-L breaking in grand unified theories.

Findings

Gravitational wave background has a flat spectrum with amplitude ~10^-8.

LIGO can potentially detect signals from B-L symmetry breaking.

Cosmic strings produce a stochastic gravitational wave background compatible with current bounds.

Abstract

The spontaneous breaking of U(1)_B-L around the scale of grand unification can simultaneously account for hybrid inflation, leptogenesis, and neutralino dark matter, thus resolving three major puzzles of particle physics and cosmology in a single predictive framework. The B-L phase transition also results in a network of cosmic strings. If strong and electroweak interactions are unified in an SO(10) gauge group, containing U(1)_B-L as a subgroup, these strings are metastable. In this case, they produce a stochastic background of gravitational waves that evades current pulsar timing bounds, but features a flat spectrum with amplitude h^2\Omega_GW ~ 10^-8 at interferometer frequencies. Ongoing and future LIGO observations will hence probe the scale of B-L breaking.