Classical and Quantum Initial Conditions for Higgs Inflation

TL;DR

This paper examines the conditions under which Higgs inflation can occur within the Standard Model, analyzing classical and quantum effects, and finds that quantum corrections may favor Starobinsky inflation unless parameters are finely tuned.

Contribution

It demonstrates that classical Higgs inflation requires no tuning under natural initial conditions, but quantum effects can shift it towards Starobinsky inflation unless parameters are tuned.

Findings

Classical Higgs inflation is achievable without tuning if initial homogeneity is assumed.

Quantum corrections necessitate additional degrees of freedom or tuning, favoring Starobinsky $R^2$ inflation.

Results are independent of the ultraviolet completion of gravity in the considered regime.

Abstract

We investigate whether Higgs inflation can occur in the Standard Model starting from natural initial conditions or not. The Higgs has a non-minimal coupling to the Ricci scalar. We confine our attention to the regime where quantum Einstein gravity effects are small in order to have results that are independent of the ultraviolet completion of gravity. At the classical level we find no tuning is required to have a successful Higgs inflation, provided the initial homogeneity condition is satisfied. On the other hand, at the quantum level we obtain that the renormalization for large non-minimal coupling requires an additional degree of freedom that transforms Higgs inflation into Starobinsky $R^2$ inflation, unless a tuning of the initial values of the running parameters is made.