On the lifetime of a cold dark matter particle and the cosmological diffuse photon background

TL;DR

This paper proposes a heavy Majorana neutrino with a mass around 100 TeV as a viable cold dark matter candidate, explaining the diffuse photon background through its long lifetime and decay mechanisms.

Contribution

It introduces a specific heavy neutrino model with a detailed decay mechanism that accounts for dark matter and the diffuse photon background.

Findings

Heavy neutrino with ~100 TeV mass is a good dark matter candidate.

The neutrino's lifetime (~10^25 s) is explained by decay suppression mechanisms.

The model aligns with cosmological density constraints.

Abstract

We show that a Majorana heavy neutrino with a mass O(100TeV) is a good candidate particle for cold dark matter. It can be responsible for the majority of the cosmological diffuse photon background owing to lifetime of the order of O(10^(25)s), dominantly fixed by the radiative two-body decay. The lifetime is suppressed by two mechanisms: the leptonic GIM cancellation and the see-saw weak coupling suppression. As a fermion cold dark matter particle, a heavy neutrino favours the average mass density of the Universe constrained by the Einstein-Cartan cosmology.