  Dark matter annihilation to leptons, $\chi \chi \rightarrow l \bar{l}$, is
necessarily accompanied by electroweak radiative corrections, in which a W or Z
boson is radiated from a final state particle. Given that the W and Z gauge
bosons decay dominantly via hadronic channels, it is thus impossible to produce
final state leptons without accompanying protons, antiprotons, and gamma rays.
Significantly, while many dark matter models feature a helicity suppressed
annihilation rate to fermions, radiating a massive gauge boson from a final
state fermion removes this helicity suppression, such that the branching ratios
Br(l \nu W), Br(l^+l^- Z), and Br(\nu\nubar Z) dominate over Br(l\bar{l}).
W/Z-bremsstrahlung thus allows indirect detection of many WIMP models that
would otherwise be helicity-suppressed, or v^2 suppressed. Antiprotons and even
anti-deuterons become consequential final state particles. This is an important
result for future DM searches. We discuss the implications of
W/Z-bremsstrahlung for "leptonic" DM models which aim to fit recent cosmic ray
positron and antiproton data.
