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

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

Approximate solutions for the skyrmion

We reconsider the Euler-Lagrange equation for the Skyrme model in the hedgehog ansatz and study the analytical properties of the solitonic solution. In view of the lack of a closed form solution to the problem, we work on approximate analytical solutions. We show that Pade approximants are well suited to continue analytically the asymptotic representation obtained in terms of a power series expansion near the origin, obtaining explicit approximate solutions for the Skyrme equations. We improve the approximations by applying the 2-point Pade approximant procedure whereby the exact behaviour at spatial infinity is incorporated. An even better convergence to the exact solution is obtained by introducing a modified form for the approximants. The new representations share the same analytical properties with the exact solution at both small and large values of the radial variable r.Comment: 15 pages, 5 figures. 1 Reference adde

Polarised parton distributions

We analyze spin dependent parton distributions consistent with the most recent measurements of the spin dependent deep inelastic scattering structure functions and obtained in the framework of the spin dilution model. Predictions for the doubly polarised proton-proton Drell-Yan asymmetry, for the high $p_{T}$ photon production mechanism and $J/\Psi$ excitation are calculated using these distributions and are shown to be particularly adequate to unveil the polarisation of partons in the proton.Comment: 13 pages and 7 figures (not included, available upon request [email protected]

Dimensional Transmutation and Dimensional Regularization in Quantum Mechanics; 1, General Theory

This is the first in a series of papers addressing the phenomenon of dimensional transmutation in nonrelativistic quantum mechanics within the framework of dimensional regularization. Transmuting potentials are completely characterized and their general properties are derived. A strategy for dimensional renormalization of these systems is presented, both for the bound-state and scattering sectors. Finally, the emergence of an energy scale from the renormalization procedure is explicitly illustrated for the two-dimensional delta-function potential

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.