Ultra High Energy Neutrino Signature in Top-Down Scenario
  Neutrinos are the best candidates to test the extreme Universe and ideas beyond the Standard Model of particle Physics. Once produced, neutrinos do not suffer any kind of attenuation by intervening radiation fields like the Cosmic Microwave Background and are not affected by magnetic fields. In this sense neutrinos are useful messengers from the far and young Universe. In the present paper we will discuss a particular class of sources of Ultra High Energy Cosmic Rays introduced to explain the possible excess of events with energy larger than the Graisen-Zatsepin-Kuzmin cut-off. These sources, collectively called top-down, share a common feature: UHE particles are produced in the decay or annihilation of superheavy, exotic, particles. As we will review in the present paper, the largest fraction of Ultra High Energy particles produced in the top-down scenario are neutrinos. The study of these radiation offers us a unique opportunity to test the exotic mechanisms of the top-down scenario. 
Roberto Aloisio (INFN - LNGS)