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New physics from ultrahigh energy cosmic rays

Subir Sarkar
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Abstract

Observations of cosmic rays with energies above ~ 4 x 10^{10} GeV have inspired several speculative suggestions concerning their origin. The crucial question is whether or not the spectrum exhibits the expected `GZK cutoff' at this energy -- concerning which there are presently contradictory results. If there is indeed a cutoff, then the sources are cosmologically distant and rather exotic in nature. If there is no cutoff then new physics is required.

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Subir Sarkar. 2003-12-16. New physics from ultrahigh energy cosmic rays. https://arxiv.org/abs/hep-ph/0312223

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