Electroweak fragmentation functions for dark matter annihilation

Electroweak corrections are relevant for dark matter indirect detection predictions. The quality of the fragmentation function approximation to describe electroweak gauge boson radiation is examined in two concrete models. For models with Majorana fermion dark matter annihilation into light fermions, the fragmentation function approximation does not work, due to the helicity suppression of the lowest-order cross section. For other models, like those with vector dark matter, fragmentation functions provide very reliable results for dark matter with masses $M_{\rm DM} \gtrsim 500$\,GeV