出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：Scattering processes in the cosmic microwave background limit the propagation of ultra high
energy charged particles in our Universe. For extragalactic proton sources resonant photopion
production results in the famous Greisen-Zatsepin-Kuzmin (GZK) cutoff at about 4×1010 GeV
expected in the spectrum observed on Earth. The faint flux of ultra high energy cosmic rays of
less than one event per year and cubic kilometer and the large systematic uncertainties in the
energy calibration of cosmic ray showers is a challenge for cosmic ray observatories and so far
the GZK cutoff has not been unambiguously confirmed. We have investigated the possibility that
the primaries of super-GZK events are strongly interacting neutrinos which are not subject to the
GZK cutoff. For the flux of protons and neutrinos from extragalactic optically thin sources and a
flexible parameterization of the neutrino-nucleon cross section we have analyzed the cosmic ray
spectra observed at AGASA and HiRes taking also into account results from horizontal events at
AGASA and contained events at RICE. We find that scenarios of strongly interacting neutrinos
are still compatible with the data requiring a steep increase of the inelastic neutrino-nucleon cross
section by four order of magnitude within one energy decade compared to the Standard Model
predictions. We also discuss the impact of the preliminary cosmic ray spectrum observed by the
Pierre Auger Observatory.
