Gravitational Waves from First-Order Phase Transitions: LIGO as a Window to Unexplored Seesaw Scales

TL;DR

This paper explores how gravitational wave signals from strong first-order phase transitions in a classically conformal neutrino mass model can be detected by LIGO, providing a new way to probe high-energy seesaw scales.

Contribution

It demonstrates that a classically conformal model predicts detectable gravitational waves from phase transitions, linking neutrino mass generation to observable signals.

Findings

A strong first-order phase transition occurs with significant supercooling.

A large portion of the model's parameter space can be excluded based on phase transition completion.

Future gravitational wave detectors like LIGO can test most of the remaining parameter space.

Abstract

Within a recently proposed classically conformal model, in which the generation of neutrino masses is linked to spontaneous scale symmetry breaking, we investigate the associated phase transition and find it to be of strong first order with a substantial amount of supercooling. Carefully taking into account the vacuum energy of the metastable minimum, we demonstrate that a significant fraction of the model's parameter space can be excluded simply because the phase transition cannot complete. We argue this to be a powerful consistency check applicable to general theories based on classical scale invariance. Finally, we show that all remaining parameter points predict a sizable gravitational wave signal, so that the model can be fully tested by future gravitational wave observatories. In particular, most of the parameter space can already be probed by the upcoming LIGO science run starting in early 2019.