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It has been argued that the observations of cosmic particles with energies in excess of $10^8$ TeV represent a puzzle. Its solution requires new astrophysics or new particle physics. We show that the latter is unlikely given that the scale associated with a new particle physics threshold must be of order 1 GeV, not TeV and above, in order to resolve the problem. In most cases such new physics should have been revealed by accelerator experiments. We examine the possibility that the highest energy cosmic rays are initiated by non-standard interactions of neutrinos in the atmosphere. We show that proposals in this direction either violate s-wave unitarity or fall short of producing a sizeable effect by several orders of magnitude.
Observation of Ultra High Energy Cosmic Rays (UHECR) -whose energy exceeds $10^20$eV- is still a puzzle for modern astrophysics. The transfer of more than 16 Joules to a microscopic particle can hardly be achieved, even in the most powerful cosmic ac
Introducing a simple Galactic wind model patterned after the solar wind we show that back-tracing the orbits of the highest energy cosmic events suggests that they may all come from the Virgo cluster, and so probably from the active radio galaxy M87.
Here in this lecture we will touch on two aspects, one the new radio methods to observe the effects of high energy particles, and second the role that radio galaxies play in helping us understand high energy cosmic rays. We will focus here on the sec
One of several working groups established for this workshop was charged with examining results and methods associated with the UHECR energy spectrum. We summarize the results of our discussions, which include a better understanding of the analysis ch
We examine the anisotropy of the arrival directions of twenty seven ultra high energy cosmic rays detected by the Pierre Auger Collaboration. We confirm the anisotropy of the arrival directions of these events and find a significant correlation with