Intense Gamma-Ray Lines from Hidden Vector Dark Matter Decay

TL;DR

This paper explores how hidden vector dark matter decays produce observable gamma-ray lines, linking theoretical decay mechanisms with potential signals detectable by gamma-ray telescopes like Fermi-LAT.

Contribution

It introduces a model where dark matter decay via dimension six operators leads to gamma-ray lines, connecting custodial symmetry breaking to observable cosmic signatures.

Findings

Gamma-ray lines from dark matter decay could be observed by Fermi-LAT.

Relic density constraints are compatible with the decay mechanism.

Direct detection rates are within current experimental sensitivities.

Abstract

Scenarios with hidden, spontaneously broken, non-abelian gauge groups contain a natural dark matter candidate, the hidden vector, whose longevity is due to an accidental custodial symmetry in the renormalizable Lagrangian. Nevertheless, non-renormalizable dimension six operators break the custodial symmetry and induce the decay of the dark matter particle at cosmological times. We discuss in this paper the cosmic ray signatures of this scenario and we show that the decay of hidden vector dark matter particles generically produce an intense gamma ray line which could be observed by the Fermi-LAT experiment, if the scale of custodial symmetry breaking is close to the Grand Unification scale. This gamma line proceeds directly from a tree level dark matter 2-body decay in association with a Higgs boson. Within this model we also perform a determination of the relic density constraints taking into account the dark matter annihilation processes with one dark matter particle in the final state. The corresponding direct detection rates can be easily of order the current experimental sensitivities.