Lorentz invariance violation and chemical composition of ultra-high energy cosmic rays

Abstract

Motivated by experimental indications of a significant presence of heavy nuclei in the cosmic ray flux at ultra high energies ( 10 19 eV), we consider the effects of Planck scale suppressed Lorentz Invariance Violation (LIV) on the propagation of cosmic ray nuclei. In particular we focus on LIV effects on the photodisintegration of nuclei onto the background radiation fields. After a general discussion of the behavior of the relevant quantities, we apply our formalism to a simplified model where the LIV parameters of the various nuclei are assumed to kinematically result from a single LIV parameter for the constituent nucleons, η, and we derive constraints on η. Assuming a nucleus of a particular species to be actually present at 10 20 eV the following constraints can be placed: −3 × 10

Searches for Lorentz Invariance Violation at the Pierre Auger Observatory

“…Violations of Lorentz symmetry could change the energy threshold of photo-hadronic interactions; in particular, depending on the composition of the UHECRs at the highest energies, the attenuation length of photo-meson production or photo-disintegration may become extremely large and suppress particle interaction during propagation in the extragalactic space [1][2][3][4]. As a consequence, the existing evidence of the suppression of the flux at the highest energies [5] can be used to put a limit on LIV.…”