On the reported detection of sub-GeV antiprotons in galactic cosmic rays

Buffington et al.¹ claim to have detected a μ/p ratio of 2.2±0.6 × 10^-4 at energies between 130 and 320 MeV. This is several orders of magnitude above theoretical predictions^2-4 at these lower energies for pμ fluxes resulting from collisions of primary cosmic rays with the interstellar gas. Measurements at higher energies by Golden et al.⁵ show a μ/p ratio of 5.2±1.5 × 10 ^-4, in excess, by a factor of about 3, of the expected values if μ;s are of secondary origin in the standard model of galactic cosmic rays. The reported μe/He ratio¹ is significantly lower than the reported μ;/p ratio, raising difficulties with some scenarios⁶ in which the μ;s are primary cosmic rays from anti-galaxies. Kiraly et al.⁷ suggest black hole evaporation as a μ; source. I discuss here scenarios in which the reported sub-GeV μ; excess might be produced as secondaries in high energy collisions. Such production must take place in compact, optically thick sources.