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The highest energy particles in the universe: the mystery and its possible solutions

Pasquale Blasi
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Abstract

The universe should be dark at energies exceeding $\sim 5\times 10^{19}$ eV. This simple but solid prediction of our best known particle physics is not confirmed by observations, that seem to suggest a quite different picture. Numerous events have in fact been detected in this energy region, with spectra and anisotropy features that defy many conventional and unconventional explanations. Is there a problem with known physics or is this a result of astrophysical uncertainties? Here we try to answer these questions, in the light of present observations, while discussing which information future observations may provide on this puzzling issue.

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Pasquale Blasi. 2001-10-31. The highest energy particles in the universe: the mystery and its possible solutions. https://arxiv.org/abs/astro-ph/0110401

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