Inflaton as a pseudo-Goldstone boson of vacuum energy shift symmetry

TL;DR

This paper proposes that the inflaton can be understood as a pseudo-Goldstone boson arising from a broken vacuum energy shift symmetry, linking cosmological inflation to symmetry breaking mechanisms.

Contribution

It introduces a novel interpretation of the inflaton as a pseudo-Goldstone boson of vacuum energy shift symmetry, connecting inflation to fundamental symmetry breaking.

Findings

Identifies the inflaton with a pseudo-Goldstone boson of vacuum energy shift symmetry.

Shows how gravity induces explicit symmetry breaking, giving the inflaton a mass.

Highlights the role of Galilean symmetry in fixing the action terms.

Abstract

The exact symmetry induced by the global shift of energy scale for the cosmological constant in the action of matter fields is spontaneously broken by setting the density of real vacuum energy and explicitly broken by the gravity that means the existence of Nambu--Goldstone boson, which transforms into the pseudo-Goldstone boson due to the gravity. We identify this boson with the inflaton in the Einstein frame of action for the fields, while the breaking is induced by a non-minimal interaction of boson with the scalar curvature in the Jordan frame. The role of Galilean symmetry of field equation is emphasized in the procedure of fixing some terms in the bare action.