The highest energy particles in the universe: the mystery and its possible solutions
Abstract
Description
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.
Invited Review Talk at "Physics in Collision", Seoul, Korea, June 28 - 30, 2001. No change in content, small changes in the references
Invited Review Talk at "Physics in Collision", Seoul, Korea, June 28 - 30, 2001. No change in content, small changes in the references