Distinguishing between R^2-inflation and Higgs-inflation

TL;DR

This paper identifies three observational features—spectral tilt, gravitational waves from scalaron dynamics, and Higgs mass ranges—that can distinguish R^2-inflation from Higgs-inflation using current and future experiments.

Contribution

The study introduces specific observational signatures to differentiate R^2-inflation from Higgs-inflation, focusing on spectral, gravitational, and particle mass predictions.

Findings

Different spectral tilt and scalar-to-tensor ratio predictions.

Gravitational waves from scalaron clump dynamics in R^2-inflation.

Higgs mass range for vacuum stability varies between models.

Abstract

We present three features which can be used to distinguish the R^2-inflation Higgs-inflation from with ongoing, upcoming and planned experiments, assuming no new physics (apart form sterile neutrinos) up to inflationary scale. (i) Slightly different tilt of the scalar perturbation spectrum n_s and ratio r of scalar-to-tensor perturbation amplitudes. (ii) Gravity waves produced within R^2-model by collapsing, merging and evaporating scalaron clumps formed in the post-inflationary Universe. (iii) Different ranges of the possible Standard Model Higgs boson masses, where the electroweak vacuum remains stable while the Universe evolves after inflation. Specifically, in the R^2-model Higgs boson can be as light as 116 GeV. These effects mainly rely on the lower reheating temperature in the R^2-inflation.