On the Importance of Electroweak Corrections for Majorana Dark Matter Indirect Detection

TL;DR

This paper demonstrates that electroweak corrections can significantly enhance the annihilation signals of Majorana dark matter particles, impacting indirect detection strategies by revealing s-wave contributions overlooked by lower-dimensional effective operators.

Contribution

It provides a detailed analysis of electroweak radiation effects on Majorana dark matter annihilation, highlighting the importance of higher-order operators in effective field theory.

Findings

Electroweak radiation can lift p-wave suppression, enabling s-wave annihilation contributions.

Enhanced fluxes of stable particles from dark matter annihilation are predicted.

Higher-order operators are necessary to accurately describe electroweak effects in effective field theory.

Abstract

Recent analyses have shown that the inclusion of electroweak corrections can alter significantly the energy spectra of Standard Model particles originated from dark matter annihilations. We investigate the important situation where the radiation of electroweak gauge bosons has a substantial influence: a Majorana dark matter particle annihilating into two light fermions. This process is in p-wave and hence suppressed by the small value of the relative velocity of the annihilating particles. The inclusion of electroweak radiation eludes this suppression and opens up a potentially sizeable s-wave contribution to the annihilation cross section. We study this effect in detail and explore its impact on the fluxes of stable particles resulting from the dark matter annihilations, which are relevant for dark matter indirect searches. We also discuss the effective field theory approach, pointing out that the opening of the s-wave is missed at the level of dimension-six operators and only encoded by higher orders.