Probing low-x QCD with cosmic neutrinos at the Pierre Auger Observatory

Abstract

The sources of the observed ultra-high energy cosmic rays must also generate ultra-high energy neutrinos. Deep inelastic scattering of these neutrinos with nucleons on Earth probe center-of-mass energies $\sqrt{s}\sim 100$ TeV, well beyond those attainable at terrestrial colliders. By comparing the rates for two classes of observable events, any departure from the benchmark (unscreened perturbative QCD) neutrino-nucleon cross-section can be constrained. Using the projected sensitivity of the Pierre Auger Observatory to quasi-horizontal showers and Earth-skimming tau neutrinos, we show that a `Super-Auger' detector can thus provide an unique probe of strong interaction dynamics.

Comments: Accepted for publication in Phys Rev D; Details of the NLO neutrino-nucleon cross-section calculation available at: http://www-pnp.physics.ox.ac.uk/~cooper/neutrino.html