Limits on Topological Defect Neutrino Fluxes from Horizontal Air Shower Measurements

We obtain the horizontal air shower rate from the (EeV) high energy neutrino flux predicted in some topological defect scenarios as the source for the highest energy cosmic rays. Emphasis is made on the different character of the events depending on the neutrino flavor an type of interaction. We show that the bound for muon poor showers in the 105 − 107 GeV energy range is violated by maximal predictions for superconducting cosmic string neutrino fluxes, we compare it to other neutrino flux limits and we discuss the future of such measurements to further constrain these models. The establishment of cosmic rays of energies above 10 eV [1] and the prospects for the construction of a giant air shower array for their study, the Pierre Auger project [2], has stimulated great activity in the search of theoretical models for the production of these particles. The annihilation of topological defects (TD’s) has been recently proposed as the origin of the highest energy cosmic rays [3] although there is some controversy about this possibility [4]. This mechanism avoids the main difficulties in the conventional shock acceleration and would imply large fluxes of gamma rays and neutrinos up to energies in the EeV range and well above [5]. Active Galactic Nuclei (AGN), the most powerful known objects, have also been suggested as the possible origin of the highest energy cosmic rays [6]. If the very high energy gamma rays detected from AGN [7] come from pion decay, in proton