W/Z bremsstrahlung as the dominant annihilation channel for dark matter, revisited

Nicole F. Bell, James B. Dent, Ahmad J. Galea, Thomas D. Jacques, Lawrence Krauss, Thomas J. Weiler

Research output: Contribution to journalArticlepeer-review

65 Scopus citations


We revisit the calculation of electroweak bremsstrahlung contributions to dark matter annihilation. Dark matter annihilation to leptons is necessarily accompanied by electroweak radiative corrections, in which a W or Z boson is also radiated. Significantly, while many dark matter models feature a helicity suppressed annihilation rate to fermions, bremsstrahlung process can remove this helicity suppression such that the branching ratios Br(ℓνW), Br(ℓ+-Z), and Br(ν̄νZ) dominate over Br(ℓ+-) and Br(ν̄ν). We find this is most significant in the limit where the dark matter mass is nearly degenerate with the mass of the boson which mediates the annihilation process. Electroweak bremsstrahlung has important phenomenological consequences both for the magnitude of the total dark matter annihilation cross section and for the character of the astrophysical signals for indirect detection. Given that the W and Z gauge bosons decay dominantly via hadronic channels, it is impossible to produce final state leptons without accompanying protons, antiprotons, and gamma rays.

Original languageEnglish (US)
Pages (from-to)6-12
Number of pages7
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Issue number1
StatePublished - Nov 30 2011


  • Dark matter annihilation

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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