Renormalization group and triviality in noncompact lattice QED with light fermions

In the framework of noncompact lattice QED with light fermions, we derive the functional dependence of the average energy per plaquette on the bare parameters using block-spin Renormalization Group arguments and assuming that the renormalized coupling vanishes. Our numerical results for this quantity in $8^4$ and $10^4$ lattices show evidence for triviality in the weak coupling phase and point to a non vanishing value for the renormalized coupling constant in the strong coupling phase.Comment: 9 page

Time delay of light signals in an energy-dependent spacetime metric

In this note we review the problem of time delay of photons propagating in a spacetime with a metric that explicitly depends on the energy of the particles (Gravity-Rainbow approach). We show that corrections due to this approach -- which is closely related to DSR proposal -- produce for small redshifts ($z<<1$) smaller time delays than in the generic Lorentz Invariance Violating case.Comment: 5 pages. This version contains two new references with respect to the published versio

THE MASS COMPOSITION OF ULTRA HIGH ENERGY COSMIC RAYS

The status of the Mass Composition measurements of Ultra High Energy Cosmic Rays is presented, with emphasis on the results from the Fluorescence Detector of the Pierre Auger Observatory. Possible consequences of the present measurements are discussed, both on the particle physics and astrophysics aspects

THE MASS COMPOSITION OF ULTRA HIGH ENERGY COSMIC RAYS

The status of the Mass Composition measurements of Ultra High Energy Cosmic Rays is presented, with emphasis on the results from the Fluorescence Detector of the Pierre Auger Observatory. Possible consequences of the present measurements are discussed, both on the particle physics and astrophysics aspects

Propagation of UHECRs in cosmological backgrounds: some results from SimProp

Ultra-High-Energy Cosmic Ray (UHECR) nuclei propagating in cosmological radiation backgrounds produce secondary particles detectable at Earth. SimProp is a one dimensional code for extragalactic propagation of UHECR nuclei, inspired by the kinetic approach of Aloisio et al. As in this approach, only a subset of nuclei and nuclear channels are used as representative. We discuss the validation of the code and present applications to UHECR experimental results. In particular we present the expected fluxes of neutrinos produced in some astrophysical scenario.Comment: Poster presented by A. Di Matteo at the 33rd International Cosmic Ray Conference, Rio De Janeiro (Brasil) July 2-9 201