Massive relic neutrinos in the galactic halo and the knee in the cosmic ray spectrum

Despite many efforts to find a reasonable explanation, the origin of the "knee" in the cosmic ray spectrum at energy around 10**15.5 eV remains mysterious. In this letter we suggest that the "knee" may be due to a GZK-like effect of cosmic rays interacting with massive neutrinos in the galactic halo. Simple kinematics connects the location of the "knee" with the mass of the neutrinos, and, while the required interaction cross section is larger than that predicted by the Standard Model, it can be accommodated by a small neutrino magnetic dipole moment. The values for the neutrino parameters obtained from the analysis of existing experimental data are compatible with present laboratory bounds.Comment: 8 pages, 1 figure, uses RevTe

Hadronic interactions models beyond collider energies

Studies of the influence of different hadronic models on extensive air showers at ultra-high energies are presented. The hadronic models considered are those implemented in the well-known QGSJET and SIBYLL event generators. The different approaches used in both codes to model the underlying physics is analyzed using computer simulations performed with the program AIRES. The most relevant observables for both single collisions and air showers are studied for primary energies ranging from $10^{14}$ eV up to $10^{20.5}$ eV. In addition, the evolution of lateral and energy distributions during the shower development is presented. Our analysis seems to indicate that the behaviour of shower observables does not largely reflect the strong differences observed in single collisions.Comment: 31 RevTex pages - 14 ps figure

Right handed currents and FSI phases in B^0 --> \phi K^{*0}

We consider possible effects of New Physics (NP) on the angular distributions of the decay B^0 --> \phi K^{*0}, showing how these effects depend on the nature of nonstandard interactions. In a general framework based on factorization, we show that triple products can be used to probe the chirality of NP currents. In this analysis we take into account the presence of non-vanishing strong phases, which is motivated by recent experimental evidence. It is seen that the observability of right-handed NP is strongly dependent on the relation between the relative magnitude of these phases and the ratio of Standard Model and NP scales. As an application we estimate the expected values of relevant observables in a particular Left Right Symmetric Model.Comment: 16 pages, no figures. Comments and references added, conclusions unchanged. Final version to appear in Phys. Rev.

Comment on "On the Origin of the Highest Energy Cosmic Rays"

We show that the photodisintegration of heavy cosmic ray nuclei with energies above 10^20 eV is dominated by interactions with photons from the cosmic microwave background radiation, rather than from infrared ones. This implies that the observed air shower events with energies 2-3 10^20 eV cannot originate from Fe nuclei coming from distances beyond 10 MpcComment: 1 page, 2 figure

Generalized Borel Transform Technique in Quantum Mechanics

We present the Generalized Borel Transform (GBT). This new approach allows one to obtain approximate solutions of Laplace/Mellin transform valid in both, perturbative and non perturbative regimes. We compare the results provided by the GBT for a solvable model of quantum mechanics with those provided by standard techniques, as the conventional Borel sum, or its modified versions. We found that our approach is very efficient for obtaining both the low and the high energy behavior of the model.Comment: 13 pages, 2 figure