Gravi-burst: super-GZK cosmic rays from localized gravity

The flux of cosmic rays beyond the GZK cutoff (∼1020 eV) may be explained through their production by ultra high energy cosmic neutrinos, annihilating on the relic neutrino background, in the vicinity of our galaxy. This process, known as the Z-burst mechanism, is mediated through the production of a Z boson at resonance. We propose a similar mechanism and call it gravi-burst, where the particles produced at resonance are the Kaluza–Klein gravitons of weak scale mass and coupling from the Randall–Sundrum hierarchy model of localized gravity. Under certain assumptions about the energy spectrum of the primary neutrinos we find that cosmic ray data could be potentially as powerful as the LHC in probing this model.