Monoenergetic Gamma-Rays from Non-Minimal Kaluza-Klein Dark Matter Annihilations

TL;DR

This paper explores gamma-ray signals from Z^1 dark matter annihilations in a non-minimal extra-dimensional model, finding enhanced rates and potential detectability with current or near-future telescopes.

Contribution

It demonstrates that non-Abelian Z^1 gauge boson annihilations produce larger gamma-ray fluxes than minimal models, with implications for dark matter detection.

Findings

Z^1 annihilation rates are significantly larger than B^1.

Predicted gamma-ray fluxes are comparable despite mass differences.

Current experiments could already constrain Z^1 dark matter with moderate boost factors.

Abstract

We investigate monoenergetic gamma-ray signatures from annihilations of dark matter comprised of Z^1, the first Kaluza-Klein excitation of the Z boson, in a non-minimal Universal Extra Dimensions model. The self-interactions of the non-Abelian Z^1 gauge boson give rise to a large number of contributing Feynman diagrams that do not exist for annihilations of the Abelian gauge boson B^1, which is the standard Kaluza-Klein dark matter candidate. We find that the annihilation rate is indeed considerably larger for the Z^1 than for the B^1. Even though relic density calculations indicate that the mass of the Z^1 should be larger than the mass of the B^1, the predicted monoenergetic gamma fluxes are of the same order of magnitude. We compare our results to existing experimental limits, as well as to future sensitivities, for image air Cherenkov telescopes, and we find that the limits are reached already with a moderately large boost factor. The realistic prospects for detection depend on the experimental energy resolution.