Electroweak bremsstrahlung for wino-like Dark Matter annihilations

Understand

If the Dark Matter is the neutral Majorana component of a multiplet which is charged under the electroweak interactions of the Standard Model, its main annihilation channel is into W+W-, while the annihilation into light fermions is helicity suppressed.

• As pointed out recently, the radiation of gauge bosons from the initial state of the annihilation lifts the suppression and opens up an s-wave contribution to the cross section.
• We perform the full tree-level calculation of Dark Matter annihilations, including electroweak bremsstrahlung, in the context of an explicit model corresponding to the supersymmetric wino.
• We find that the fermion channel can become as important as the di-boson one.