Distinctive positron feature from particle dark-matter annihilations in the galatic halo

If the dark matter in our galactic halo consists of weakly interacting massive particles (WIMP's) heavier than the W^ boson which have a significant annihilation branch into W^ and Z^0 pairs, e. g. , a Higgsino-like neutralino, a very distinctive feature in the cosmic-ray positron spectrum arises from W^+ and Z^0 decays. Because of inherent astrophysical uncertainties such a signal is by no means guaranteed even if heavy WIMP's do comprise the galactic halo. However, the positron signature is virtually a "smoking gun" for particle dark matter in the halo and thus worthy of note.