Testing effects of Lorentz invariance violation in the propagation of astroparticles with the Pierre Auger Observatory

Abstract

Lorentz invariance violation (LIV) is often described by dispersion relations of the formwith delta different based on particle type i, with energy E, momentum p and rest mass m. Kinematics and energy thresholds of interactions are modified once the LIV terms become comparable to the squared masses of the particles involved. Thus, the strongest constraints on the LIV coefficients δ i,n tend to come from the highest energies. At sufficiently high energies, photons produced by cosmic ray interactions as they propagate through the Universe could be subluminal and unattenuated over cosmological distances. Cosmic ray interactions can also be modified and lead to detectable fingerprints in the energy spectrum and mass composition observed on Earth. The data collected at the Pierre Auger

Ultra-High-Energy Cosmic Rays: The Intersection of the Cosmic and Energy Frontiers

“…This provides an interesting link to funda-mental cosmological aspects, such as the Hubble rate and the curvature of space-time [18]. The search for photons has also served to constrain physics beyond the Standard Model, for instance models that violate Lorentz invariance [274][275][276][277]9].…”

“…Searches for non-zero values of η (n) i can be used to constrain MDR coefficients for various particle types (see e.g., Refs. [9][10][11][12][13][14][15][16][17]). LIV can cause certain photonuclear processes which are allowed for non-relativistic nuclei to be forbidden for an ultra-relativistic ones, or vice versa (and some processes can be allowed in both cases but with different rates).…”

“…Either way, this will allow for further improvements to the constraints on models of UHECR sources [60, and refs. therein] and on certain exotic scenarios (see e.g., [9,270,532]).…”

“…• Is Lorentz invariance (still) valid under such conditions [924,13,[925][926][927][928]9]? • How do these particles interact?…”

“…In such kind of studies, a significant increase of the sensitivity is obtained by adding information on mass composition [925]. The combined fit of the spectral shape and of the composition has been used by the Auger collaboration to set stringent limits on the LIV amplitude [9]. A significant increase in statistics together with an improvement in mass sensitivity for future observatories will be extremely beneficial to improve such limits.…”