Multifield Stochastic Dynamics in GUT Hybrid Inflation and Gravitational Wave Signatures of GUT Higgs Representation

TL;DR

This paper explores how stochastic quantum fluctuations in GUT hybrid inflation can generate observable gravitational waves, linking their amplitude to the GUT Higgs representation, and offers a new way to probe GUT Higgs properties.

Contribution

It introduces a detailed analysis of stochastic effects in GUT hybrid inflation, showing how these fluctuations produce detectable gravitational waves related to the Higgs field's degrees of freedom.

Findings

Gravitational wave amplitude inversely proportional to GUT Higgs degrees of freedom

Waterfall phase transition can extend over several e-foldings to dilute monopoles

Observable gravitational waves can be produced without overproducing primordial black holes

Abstract

We revisit the hybrid inflation model within the framework of the Grand Unified Theory (GUT), focusing on cases where the waterfall phase transition extends over several e-foldings to dilute monopoles. Considering the stochastic effects of quantum fluctuations, we demonstrate that the waterfall fields (i.e., GUT Higgs) maintain a nonzero vacuum expectation value around the waterfall phase transition. By accurately accounting for the number of degrees of freedom of the GUT Higgs field, we establish that these fluctuations can produce observable gravitational waves without leading to an overproduction of primordial black holes. The amplitude of these gravitational waves is inversely proportional to the degrees of freedom of the waterfall fields, thereby providing a unique method to probe the representation of the GUT Higgs.