Limits on beyond standard model messengers as ultra high energy cosmic rays

Oscar Castillo-Felisola, Cristobal Corral, Piotr Homola, Jilberto Zamora-Saa

Published 2017-09-26Version 1

Up to date, there is no confirmed theoretical explanation for the ultra-high energy cosmic rays (UHECR) beyond the Greisen-Zatsepin-Kuzmin (GZK) limit. In order for these UHECRs to reach the Earth, it is required an extremely suppressed interaction between them and the cosmic microwave background (CMB), which is impossible for standard model (SM) particles, except neutrinos. In this letter, we present constraints on the parameter space of models involving axion-like particles and dark photons, as candidates for UHECRs, by considering that these particles can traverse the visible Universe without decaying. In the case of axion-like particles, the constraints are tighter than those given in previous works. We present for the first time constraints on the parameter space of dark photon models, by considering their kinetic term mixing with SM photons.