Constraints on dark matter annihilation to fermions and a photon

TL;DR

This paper investigates Majorana dark matter annihilation into fermions and a photon using effective field theory, revealing interference effects and deriving constraints from indirect detection, relic density, and collider data.

Contribution

It introduces a combined analysis of dimension 6 and 8 operators in dark matter annihilation, highlighting their interference effects and deriving new constraints on the effective scale.

Findings

Interference between operators causes cancellation in annihilation channels.

Constraints on the effective cutoff scale are established from multiple experimental sources.

Heavier dark matter masses are dominated by dimension 8 operators.

Abstract

We consider Majorana dark matter annihilation to fermion - anti-fermion pair and a photon in the effective field theory paradigm, by introducing dimension 6 and dimension 8 operators in the Lagrangian. For a given value of the cut-off scale, the latter dominates the annihilation process for heavier dark matter masses. We find a cancellation in the dark matter annihilation to a fermion - anti-fermion pair when considering the interference of the dimension 6 and the dimension 8 operators. Constraints on the effective scale cut-off is derived while considering indirect detection experiments and the relic density requirements and they are compared to the bound coming from collider experiments.