Particle theory

Abstract:

This article introduces definitions for a number of new event shapes and jet-rates in hadron-hadron dijet production. They are designed so as to be measurable in practice at the Tevatron and the LHC, and to be global so that they can be resummed with currently available techniques. We explain how to vary their sensitivity to beam fragmentation, limiting its impact for purely perturbative studies, or deliberately enhancing it so as to focus on non-perturbative effects. Explicit next-to-leading logarithmic resummed results are presented, as obtained with CAESAR. © SISSA/ISAS 2004.

Abstract:

As ultra-high energy cosmic ray protons propagate through the universe, they undergo photo-meson interactions with the cosmic microwave background, generating the `cosmogenic' neutrino flux. If a substantial fraction of the cosmic ray primaries are heavy nuclei rather than protons, however, they would preferentially lose energy through photo-disintegration, so the corresponding neutrino flux may be substantially depleted. We investigate this issue using a Monte Carlo simulation of cosmic ray propagation through interagalactic radiation fields and assess the impact of the altered neutrino fluxes on next generation neutrino telescopes.