Non-thermal Production of PNGB Dark Matter and Inflation

TL;DR

This paper explores a pseudo Nambu-Goldstone boson as a dark matter candidate produced non-thermally via inflaton decay, and investigates its potential role as the inflaton itself, linking dark matter and inflation in a unified framework.

Contribution

It introduces a model where the pNGB acts as both dark matter and inflaton, with relic abundance generated through non-thermal production mechanisms.

Findings

pNGB dark matter mass should be less than a few GeV.

Non-thermal production via inflaton decay can account for relic abundance.

Unified inflaton and dark matter scenario is viable with large symmetry breaking scale.

Abstract

A pseudo Nambu-Goldstone boson (pNGB) is a natural candidate of dark matter in that it avoids the severe direct detection bounds. We show in this paper that the pNGB has another different and interesting face with a higher symmetry breaking scale. Such large symmetry breaking is motivated by various physics beyond the standard model. In this case, the pNGB interaction is suppressed due to the Nambu-Goldstone property and the freeze-out production does not work even with sufficiently large portal coupling. We then study the pNGB dark matter relic abundance from the out-of-equilibrium production via feeble Higgs portal coupling. Further, a possibility is pursued the symmetry breaking scalar in the pNGB model plays the role of inflaton. The inflaton and dark matter are unified in a single field and the pNGB production from inflaton decay is inevitable. For these non-thermally produced relic abundance of pNGB dark matter and successful inflation, we find that the dark matter mass should be less than a few GeV in the wide range of the reheating temperature and the inflaton mass.