Looking for Dark Matter in All the Wrong Places

David Harris at symmetry breaking points to a paper and accompanying commentary on the search for high-energy cosmic antiprotons by the PAMELA satellite experiment. (What one defines as "high-energy" depends on one's upbringing; we're talking about energies of up to 100 times the mass of the proton.) The impression is given that this is a brand-new result casting doubt on the earlier claims that PAMELA might have detected evidence for dark matter; that's not really a correct impression, so it's worth getting it all straight. The PAMELA satellite, an Italian/Russian/German/Swedish collaboration, looks at high-energy cosmic rays from orbit, and pays particular attention to the presence of antimatter -- basically, positrons (anti-electrons) and anti-protons. Part of the idea is that a high-energy matter particle can simply be a particle that had been lying around for a while and was accelerated to large velocities by magnetic fields or other astrophysical processes, whereas ...