Non-perturbative reheating and Nnaturalness

TL;DR

This paper explores non-perturbative reheating mechanisms in inflationary models, highlighting how small couplings and negative mass squared scalars can enhance reheating efficiency and support the Nnaturalness solution to the hierarchy problem.

Contribution

It introduces models where non-perturbative effects dominate reheating, demonstrating how light scalars and sector couplings can address the hierarchy problem within cosmological constraints.

Findings

Reheating can be exponentially suppressed or enhanced depending on scalar masses.

A light Higgs sector can dominate reheating, leaving other sectors minimally energized.

The inflaton can have a flat potential, raising the UV cutoff to 10 TeV.

Abstract

We study models in which reheating happens only through non-perturbative processes. The energy transferred can be exponentially suppressed unless the inflaton is coupled to a particle with a parametrically small mass. Additionally, in some models a light scalar with a negative mass squared parameter leads to much more efficient reheating than one with a positive mass squared of the same magnitude. If a theory contains many sectors similar to the Standard Model coupled to the inflaton via their Higgses, such dynamics can realise the Nnaturalness solution to the hierarchy problem. A sector containing a light Higgs with a non-zero vacuum expectation value is dominantly reheated and there is little energy transferred to the other sectors, consistent with cosmological constraints. The inflaton must decouple from other particles and have a flat potential at large field values, in which case the visible sector UV cutoff can be raised to 10 TeV in a simple model.