Distinguishing Higgs inflation and its variants

TL;DR

This paper explores how to observationally differentiate Higgs Inflation from gauge singlet scalar inflation models by analyzing spectral index variations and the impact of Higgs mass measurements.

Contribution

It provides a method to distinguish Higgs inflation from singlet scalar inflation using spectral index measurements and Higgs mass data.

Findings

Spectral index n decreases with Higgs mass if Higgs is the inflaton.

Spectral index n increases with Higgs mass if a gauge singlet scalar is the inflaton.

A combination of Higgs mass and spectral index measurements can distinguish the models.

Abstract

We consider how Higgs Inflation can be observationally distinguished from variants based on gauge singlet scalar extensions of the Standard Model, in particular where the inflaton is a non-minimally coupled gauge singlet scalar (S-inflation). We show that radiative corrections generally cause the spectral index n to decrease relative to the classical value as the Higgs mass is increased if the Higgs boson is the inflaton, whereas n increases with increasing Higgs mass if the inflaton is a gauge singlet scalar. The accuracy to which n can be calculated in these models depends on how precisely the reheating temperature can be determined. The number of Einstein frame e-foldings N is similar in both models, with N = 58-61 for singlet inflation compared with N = 57-60 for Higgs inflation. This allows the spectral index to be calculated to an accuracy \Delta n = 0.001. Provided the Higgs mass is above ~ 135 GeV, a combination of a Higgs mass measurement and a precise determination of n will enable Higgs Inflation and S-inflation to be distinguished.