Tau energy losses at ultra-high energy: continuous versus stochastic treatment

We study the energy losses of the tau lepton in matter through electromagnetic processes at ultra-high energy (UHE). We use both a stochastic and a continuous framework to treat these interactions and compare the flux of tau leptons propagated after some amount of matter. We discuss the accuracy of the approximation of continuous energy losses by studying the propagation in standard rock of taus with both mono-energetic and power law injection spectra.Comment: 7 pages, 8 figure

INFLUENCE OF THE RESULTS OF UHECR DETECTION ON THE LHC EXPERIMENTS

The cosmic ray energy region 1015 ÷ 1017TeV corresponds to LHC energies 1 ÷ 14TeV in the center-of-mass system. The results obtained in cosmic rays (CR) in this energy interval can therefore be used for developing new approaches to the analysis of experimental data, for interpreting the results, and for planning new experiments. The main problem in cosmic ray investigations is the remarkable excess of muons, which increases with energy and cannot be explained by means of contemporary theoretical models. Some possible new explanations of this effect and other unusual phenomena observed in CR, and ways of searching for them in the LHC experiments are discussed

Results of a search for monopoles and tachyons in horizontal cosmic ray flux

A search for monopoles and tachyons at ground level was carried out using an arrangement consisting of an ionization calorimeter and two hodoscope detectors. No clear evidence for these particles was obtained. The flux of monopoles with velocities beta approximately 0.01 is found to be less than 5.1 x 10 to the minus 13th power square centimeters s(-1) sr(-1) (95% cl.). The upper limit on the tachyon flux density is set as a 6 x 10 the minus 9th power particle/square centimeter event

Energy spectrum of cascade showers induced by cosmic ray muons in the range from 50 GeV to 5 TeV

The energy spectrum of cascade showers induced by electromagnetic interactions of high energy muons of horizontal cosmic ray flux in iron absorber was measured. The total observation time exceeded 22,000 hours. Both the energy spectrum and angular distributions of cascade showers are fairly described in terms of the usual muon generation processes, with a single power index of the parent meson spectrum over the muon energy range from 150 GeV to 5 TeV

Weak interactions of supersymmetric staus at high energies

Neutrino telescopes may have the potential to detect the quasi-stable staus predicted by supersymmetric models. Detection depends on stau electromagnetic energy loss and weak interactions. We present results for the weak interaction contribution to the energy loss of high energy staus as they pass through rock. We show that the neutral current weak interaction contribution to the energy loss increases with energy, but it is much smaller than the photonuclear energy loss, however, the charged current contribution may become the dominant process above the energy of $\sim 10^9$ GeV, depending on the parameters of the model. As a consequence, the stau range may be reduced above $\sim 10^9$ GeV as compared to the range neglecting weak interactions. We contrast this with the tau range which is barely changed with the inclusion of charged current interactions.Comment: 7 pages, 8 figures, version to be publishe

Charged Current Neutrino Cross Section and Tau Energy Loss at Ultra-High Energies

We evaluate both the tau lepton energy loss produced by photonuclear interactions and the neutrino charged current cross section at ultra-high energies, relevant to neutrino bounds with Earth-skimming tau neutrinos, using different theoretical and phenomenological models for nucleon and nucleus structure functions. The theoretical uncertainty is estimated by taking different extrapolations of the structure function F2 to very low values of x, in the low and moderate Q2 range for the tau lepton interaction and at high Q2 for the neutrino-nucleus inelastic cross section. It is at these extremely low values of x where nuclear shadowing and parton saturation effects are unknown and could be stronger than usually considered. For tau and neutrino energies E=10^9 GeV we find uncertainties of a factor 4 for the tau energy loss and of a factor 2 for the charged current neutrino-nucleus cross section.Comment: 20 pages and 11 figure