Quantum Gravity Phenomenology Induced in the Propagation of UHECR, a Kinematical Solution in Finsler and Generalized Finsler Spacetime
Abstract
It is wellknown that the Universe is opaque to the propagation of UltraHighEnergy Cosmic Rays (UHECRs) since these particles dissipate energy during their propagation interacting with the Cosmic Microwave Background (CMB) mainly in the socalled GZK cutoff phenomenon. Some experimental evidence seems to hint at the possibility of a dilation of the GZK predicted opacity sphere. It is wellknown that kinematical perturbations caused by supposed quantum gravity (QG) effects can modify the foreseen GZK opacity horizon. The introduction of Lorentz Invariance Violation (LIV) can indeed reduce, in some cases making negligible, the CMBUHECRs interaction probability. In this work we explore the effects induced by modified kinematics in the UHECRs phenomenology from the QG perspective. We explore the possibility of a geometrical description of the massive fermions interaction with the supposed quantum structure of spacetime in order to introduce a Lorentz covariance modifification. The kinematics is amended modifying the Dispersion Relations (DRs) of free particles in the context of a covariancepreserving framework. This spacetime description requires a more general geometry than the usual Riemannian one, indicating for instance the Finsler construction and the related generalized Finsler spacetime as ideal candidates. Finally we investigate the correlation between the magnitude of Lorentz covariance modification and the attenuation length of the photopion production process related to the GZK cutoff, demonstrating that the predicted opacity horizon can be dilated even in the context of a theory that does not require any privileged reference frame.
 Publication:

Galaxies
 Pub Date:
 November 2021
 DOI:
 10.3390/galaxies9040103
 arXiv:
 arXiv:2110.09184
 Bibcode:
 2021Galax...9..103T
 Keywords:

 General Relativity and Quantum Cosmology;
 High Energy Physics  Theory