Minimal Higgs inflation

TL;DR

This paper introduces two minimal Higgs inflation models with modified potentials that produce flat inflationary plateaus, fitting cosmological data well and predicting very low tensor-to-scalar ratios, without requiring non-minimal couplings.

Contribution

The authors propose simple minimal Higgs inflation scenarios through potential modifications, avoiding non-minimal Higgs-gravity couplings, and demonstrate their consistency with observational data.

Findings

Inflation energy scale around 10^{14} to 10^{15} GeV.

Predicted scalar spectral index n_s=0.968 and e-foldings N=47-52.

Tensor-to-scalar ratio r is below 10^{-5}, undetectable soon.

Abstract

In this paper we propose two simple minimal Higgs inflation scenarios through a simple modification of the Higgs potential, as opposed to the usual non-minimal Higgs-gravity coupling prescription. The modification is done in such a way that it creates a flat plateau for a huge range of field values at the inflationary energy scale $\mu \simeq (\lambda)^{1/4} \alpha$. Assuming the perturbative Higgs quartic coupling, $\lambda \simeq {\cal O}(1)$, for both the models inflation energy scale turned out to be $\mu \simeq (10^{14}, 10^{15})$ GeV, and prediction of all the cosmologically relevant quantities, $(n_s,r,dn_s^k)$, fit extremely well with observations made by PLANCK. Considering observed central value of the scalar spectral index, $n_s= 0.968$, our two models predict efolding number, $N = (52,47)$. Within a wide range of viable parameter space, we found that the prediction of tensor to scalar ratio $r (\leq 10^{-5})$ is far below the current experimental sensitivity to be observed in the near future. The prediction for the running of scalar spectral index, $dn_s^k$, approximately remains the same as was predicted by the usual chaotic and quartic inflation scenario. We also the computed the background field dependent unitarity scale $\Lambda(h)$, which turned out to be much larger than the aforementioned inflationary energy.