The Ultra High Energy Cosmic Ray Spectrum from Relic Particle Decay and DGLAP Evolution

Abstract

We calculate the spectrum of ultra high energy cosmic rays produced by the decay of a superheavy dark matter population clustered in the galactic halo. To perform this calculation we start with fragmentation functions measured at LEP and evolve them to the cosmic ray energy scale using the QCD DGLAP equations. We consider Standard Model evolution and supersymmetric evolution. We also take into account many-body final states in the decay of the dark matter particles.