The Top--Down Interpretation of Ultra--High Energy Cosmic Rays

Abstract

The origin of Ultra--High Energy ($E \gsim 10^{20}$ eV) Cosmic Rays (UHECR) remains mysterious. I discuss ``top--down'' models, where UHECR originate from the decay of very massive, long--lived particles. I summarize the calculation of the spectrum of decay products, discuss possible problems with this scenario, and describe ways to test it by searching for very energetic neutrinos and neutralinos.

arXiv commentLaTeX, 6 pages; invited talk at VHEPA-3, ICRR, Tokyo, March 2003