Post-GZK Air Showers, FCNC, Strongly Interacting Neutrinos and Duality

Abstract

A review is given on the recently proposed idea that air showers with energy $> 10^{20}$ eV beyond the Greisen-Zatsepin-Kuz'min cut-off may be due to neutrinos having acquired a strong interaction at these energies, as suggested by the Dualized Standard Model. Such a hypothesis is shown to be consistent with the so far known facts. Further, by linking the astrophysical puzzle of post-GZK air showers through electric-magnetic duality to the problem of fermion generations in particle physics, one obtains on the one hand estimates for the rates of some flavour-changing neutral current decays which are accessible to experiments being planned, and on the other direct tests on the hypothesis performable by new air shower detectors such as Auger. The suggestion does not exclude other explanations for post-GZK showers given in the literature. However, we diagree with a recent paper by Burdman, Halzen and Gandhi which sweepingly claimed to have excluded nearly all explanations by new particle physics including ours.