Modification of the mean free path of very high energy photons due to a relativistic deformed kinematics

Abstract

Ultra-high-energy physics is about to enter a new era thanks to the impressive results of experiments such as the Large High Altitude Air Shower Observatory (LHAASO), detecting photons of up to 1.4 PeV (10 15 eV). These new results could be used to test deviations with respect to special relativity. While this has been already explored within the approach of Lorentz invariance violation (LIV) theories, in this work we consider, for the first time, modifications of a relativistic deformed kinematics (which appear in doubly special relativity, or DSR, theories). In particular, we study the mean free path of very high-energy photons due to electron-positron pair creation when interacting with low-energy photons of the cosmic microwave background. Depending on the energy scale of the relativistic deformed kinematics, present (or near future) experiments can be sensitive enough to be able to identify deviations from special relativity.

Cosmic Neutrinos as a Window to Departures from Special Relativity

“…The compatibility with the relativity principle, in comparison with the case of LIV, can be shown to produce a cancellation of the effects of the two modifications. Therefore, in order to have an observable consequence of the deformation of the kinematics in a process, one has to consider energies comparable to the energy scale Λ of the deformation [45][46][47][48][49]. This means that in order to have a signal of DSR in the particle processes which are relevant in high-energy astrophysics, and in particular, in the observations of cosmic neutrinos, it is necessary to consider an energy scale parametrizing the deformation of the kinematics of the order of the energy involved in those processes.…”

“…These decays are processes whose kinematics, including the effects of LIV [58] or DSR [49], can be systematically studied. In the SR case, the standard way to proceed is to consider the decay in the rest frame of the decaying particle, and then go to the laboratory frame by applying a boost with a very large Lorentz factor corresponding to the very high energy of the decaying particle.…”