Enhancement of Majorana Dark Matter Annihilation Through Higgs Bremsstrahlung

Abstract

For Majorana dark matter, gauge boson bremsstrahlung plays an important role in enhancing an otherwise helicity-suppressed s-wave annihilation cross-section. This is well known for processes involving a radiated photon or gluon together with a Standard Model fermion-antifermion pair, and the case of massive electroweak gauge bosons has also recently been studied. Here we show that internal Higgs bremsstrahlung also lifts helicity suppression and could be the dominant contribution to the annihilation rate in the late Universe for dark matter masses below ~1 TeV. Using a toy model of leptophilic dark matter, we calculate the annihilation cross-section into a lepton-antilepton pair with a Higgs boson and investigate the energy spectra of the final stable particles at the annihilation point.

17 pages, 7 figures

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Cited by in corpus (8)

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• Coloured coannihilations: Dark matter phenomenology meets non-relativistic EFTs
• Prospects for discovering a neutrino line induced by dark matter annihilation
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• Searching for lepton portal dark matter with colliders and gravitational waves
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