Photon interaction with matter: Is there a threshold at multi-TeV energy?

Abstract

Claims of new phenomena at multi-TeV energy, which cannot be accounted for by the sub-TeV particle physics based on accelerator experiments, come from (a) observations of muons from cosmic point sources (such as Cygnus X-3) and (b) anomalies in cosmic ray interactions with primary energies in excess of 100 TeV (such as Centauro events). In examining these claims we find a common pattern emerging from these seemingly unrelated phenomena pointing at a novel interaction mechanism of photons with matter. The features of this new threshold possibly observed with cosmic photon beams of O(10 TeV), are reflected in the behavior of secondary photons from π 0 decays in hadronic collisions of O(100 TeV) primary energy. We try to define the precise issues implied by these observations so that they can be scrutinized by future accelerator or non-accelerator experiments.