Higgs-like spectator field as the origin of structure

TL;DR

This paper proposes that a Higgs-like spectator scalar field during inflation can generate the primordial density perturbations through indirect modulation of reheating, producing observable non-Gaussianity.

Contribution

It introduces a novel mechanism where a Higgs-like spectator field sources primordial perturbations without direct coupling to the inflaton or non-renormalisable interactions.

Findings

Spectator field can produce observed perturbations with local non-Gaussianity of f_NL ≈ 5.

The Higgs-like field scenario is viable in extended models with right-handed neutrinos.

Standard Model alone does not produce the observed perturbations in this framework.

Abstract

We show that the observed primordial perturbations can be entirely sourced by a light spectator scalar field with a quartic potential, akin to the Higgs boson, provided that the field is sufficiently displaced from vacuum during inflation. The framework relies on the indirect modulation of reheating, which is implemented without any direct coupling between the spectator field and the inflaton and does not require non-renormalisable interactions. The scenario gives rise to local non-Gaussianity with $f_{\rm NL}\simeq 5$ as the typical signal. As an example model where the indirect modulation mechanism is realised for the Higgs boson, we study the Standard Model extended with right-handed neutrinos. For the Standard Model running we find, however, that the scenario analysed does not seem to produce the observed perturbation.