TeV Strings and Ultrahigh-Energy Cosmic Rays

Abstract

The origin and nature of ultrahigh-energy cosmic ray events, above the Greisen-Zatsepin-Kuzmin (GZK) cutoff energy, constitute a long-standing, unsolved mistery. Neutrinos are proposed candidates but their standard interactions with matter are too weak. In the context of a TeV-scale string theory, motivated by possible extra space dimensions, the neutrino-nucleon scattering is examined. Resonant string contributions increase substantially the standard model neutrino-nucleon cross section. Although they seem insufficient to explain the trans-GZK cosmic ray events, their effects might be detected in next experiments.

12 pages, LaTeX, 2 figures; talk presented at the XXV International School of Theoretical Physics, Ustron, Poland, September 10-16, 2001. Discussion on gravity versus gauge effects improved