Cosmic Rays and New Physics at the TeV: the Neutrino-Nucleon Cross Section

Ultrahigh energy neutrinos can be used to explore the physics at the TeV scale. We study the neutrino-nucleon cross section in models with extra dimensions and the fundamental scale at the TeV. In particular, we discuss the production of string resonances and the gravitational interactions (multigraviton exchange and production of microscopic black holes) in these models. We show that the new TeV physics could give observable signals in horizontal air showers and neutrino telescopes.