Observational signatures of Higgs inflation

TL;DR

This paper examines how Higgs inflation's predictions depend on the matching between low-energy Standard Model parameters and high-energy inflationary physics, highlighting the importance of the top quark mass and potential features in the inflationary potential.

Contribution

It analyzes the sensitivity of Higgs inflation predictions to non-renormalisable matching conditions and identifies parameter ranges where the model remains consistent or falsifiable.

Findings

For top mass $m_t extgreater 171.8$ GeV, predicts $n_s hickapprox 0.97$ and $r hickapprox 0.003$

Matching requires a Higgs coupling jump $ hicksim 0.01$ below inflation scale

Negative running of spectral index $ extless -0.01$ would rule out Higgs inflation

Abstract

We investigate the dependency of Higgs inflation on the non-renormalisable matching between the low energy Standard Model limit and the inflationary regime at high energies. We show that for the top mass range $m_t \gtrsim 171.8$ GeV the scenario robustly predicts the spectral index $n_s \simeq 0.97$ and the tensor-to-scalar ratio $r\simeq 0.003$. The matching is however non-trivial, even the best-fit values $m_h=125.09$ GeV and $m_t=173.21$ GeV require a jump $\delta \lambda \sim 0.01$ in the Higgs coupling below the inflationary scale. For $m_t\lesssim 171.8$ GeV, the matching may generate a feature in the inflationary potential. In this case the predicted values of $n_s$ and $r$ vary but the model is still falsifiable. For example, a detection of negative running of spectral index at level $\alpha_s \lesssim -0.01$ would rule out Higgs inflation.