Goldstone bosons and a dynamical Higgs field

TL;DR

This paper demonstrates that Goldstone bosons contribute to the one-loop effective action in Higgs inflation models, highlighting the importance of gauge invariance and proper gauge choice in quantum corrections.

Contribution

It shows that Goldstone bosons affect the effective action in Higgs inflation, correcting previous unitary gauge calculations by using a gauge-invariant approach.

Findings

Goldstone bosons contribute to the effective action during inflation.

Unitary gauge calculations can be incorrect without accounting for Goldstone contributions.

The approach ensures gauge invariance of the effective action.

Abstract

Higgs inflation uses the gauge variant Higgs field as the inflaton. During inflation the Higgs field is displaced from its minimum, which results in associated Goldstone bosons that are apparently massive. Working in a minimally coupled U(1) toy model, we use the closed-time-path formalism to show that these Goldstone bosons do contribute to the one-loop effective action. Therefore the computation in unitary gauge gives incorrect results. Our expression for the effective action is gauge invariant upon using the background equations of motion.