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The space-borne antimatter experiment PAMELA has recently reported asurprising rise in the positron to electron ratio at high energies. It has alsorecently been found that electromagnetic radiative corrections in some casesmay boost the gamma-ray yield from supersymmetric dark matter annihilations inthe galactic halo by up to three or four orders of magnitude, providingdistinct spectral signatures for indirect dark matter searches to look for.Here, we investigate whether the same type of corrections can also lead tosizeable enhancements in the positron yield. We find that this is indeed thecase, albeit for a smaller region of parameter space than for gamma rays;selecting models with a small mass difference between the neutralino andsleptons, like in the stau coannihilation region in mSUGRA, the effect becomesmore pronounced. The resulting, rather hard positron spectrum with a relativelysharp cutoff may potentially fit the rising positron ratio measured by thePAMELA satellite. To do so, however, very large "boost factors" have to beinvoked that are not expected in current models of halo structure. If thepredicted cutoff would also be confirmed by later PAMELA data or upcomingexperiments, one could either assume non-thermal production in the earlyuniverse or non-standard halo formation to explain such a spectral feature asan effect of dark matter annihilation. At the end of the paper, we brieflycomment on the impact of radiative corrections on other annihilation channels,in particular antiprotons and neutrinos.

New Positron Spectral Features from Supersymmetric Dark Matter - a Way to Explain the PAMELA Data?