Ultra High-Energy Interaction of CR protons

TL;DR

This paper explores the high-energy interactions of cosmic ray protons, analyzing whether they are primarily protons or heavy nuclei, and discusses implications for cosmic ray propagation models.

Contribution

It investigates the possibility that extragalactic cosmic rays are mainly heavy nuclei, challenging the conventional proton interpretation and examining the impact on interaction models.

Findings

Protons may not be the primary extragalactic cosmic rays.

Interaction parameters like mean-free-path and inelasticity are critical for understanding propagation.

Exotic interaction possibilities are considered to resolve observational discrepancies.

Abstract

The recent Auger results suggest that although coincidences of arrival directions with 'nearby' AGN and HiRes discovery of the GZK cut-off indicate protons, the measured longitudinal propagation characteristics indicate heavy nuclei, if the conventional interaction model is correct. Something has to change! Our own view is that it is possible that the AGN -implied proton identification is not correct and that the extra galactic particles are, in fact, mainly 'heavies', in which case the interaction problem goes away. However, here we assume that the particles ARE protons and examine the possible consequences. Parameters discussed include the interaction mean-free-path, inelasticities and 'exotic' possibilities.