Search for ultra-high energy neutrinos with the Pierre Auger Observatory and other experiments

The Pierre Auger Observatory has the capability of detecting ultra-high energy neutrinos of all flavours. They interact through charged and neutral currents in the atmosphere (downward-going) and through the 'Earth-skimming' mechanism (upward-going). The main challenge in detecting ultra-high energy neutrinos (UHEν) with the Pierre Auger Observatory is to identify a neutrino-induced shower in the overwhelming background of showers initiated by ultra-high energy cosmic rays, possibly protons, heavy nuclei or even photons. While these backgrounds interact shortly after entering the atmosphere, neutrinos can generate deep showers, so the method adopted is to search for very inclined young showers. At ground level, neutrino events would have significant electromagnetic component leading to a broad time structure of detected signals in the water-Cherenkov detectors of the Auger surface array, in contrast to nucleonic induced showers. In this document we present the neutrino search analysis, discuss sources of background and systematic uncertainties and place the corresponding limits on the neutrino fluxes. Results from other UHE neutrino experiments are also reviewed.