Primordial non-Gaussianity from the Effects of the Standard Model Higgs during Reheating after Inflation

TL;DR

This paper explores how the Standard Model Higgs field during inflation can cause observable non-Gaussian temperature anisotropies in the CMB through inhomogeneous reheating, providing a novel probe of high-energy Higgs dynamics.

Contribution

It introduces a new method to study the Higgs potential at high energies by linking Higgs fluctuations during inflation to CMB non-Gaussianity constraints.

Findings

Higgs fluctuations induce space-dependent reheating efficiency.

Resulting temperature anisotropies have a significant non-Gaussian component.

Current Planck data constrains Higgs-related non-Gaussianity, limiting Higgs influence on observed anisotropies.

Abstract

We propose a new way of studying the Higgs potential at extremely high energies. The Standard Model (SM) Higgs boson, as a light spectator field during inflation in the early Universe, can acquire large field values from its quantum fluctuations which vary among different causal (Hubble) patches. Such a space dependence of the Higgs after the end of inflation leads to space-dependent SM particle masses and hence variable efficiency of reheating, when the inflaton decays to Higgsed SM particles. Inhomogeneous reheating results in (observable) temperature anisotropies. Further, the resulting temperature anisotropy spectrum acquires a significant non-Gaussian component, which is constrained by $\textit{Planck}$ observations of the Cosmic Microwave Background (CMB) and potentially detectable in next-generation experiments. Constraints on this non-Gaussian signal largely exclude the possibility of the observed temperature anisotropies arising primarily from Higgs effects. Hence, in principle, observational searches for non-Gaussianity in the CMB can be used to constrain the dynamics of the Higgs boson at very high (inflationary) energies.