Can there be neutrino oscillation in Gamma-Ray Bursts fireball ?

The central engine which powers the Gamma-Ray Burst (GRB) fireball, produces neutrinos in the energy range of about 5-20 MeV. Fractions of these neutrinos may propagate through the fireball which is far away from the central engine. We have studied the propagation of these neutrinos through the fireball which is contaminated by baryons and have shown that, resonant conversion of neutrinos are possible for the oscillations of nu_e to nu_{mu,tau}, nu_e to nu_s and anti-nu_(mu,tou) to anti-nu_s if the neutrino mass square difference and mixing angle are in the atmospheric and/or LSND range. On the other hand it is probably difficult for neutrinos to have resonant oscillation if the neutrino parameters are in the solar neutrino range. From the resonance condition we have estimated the fireball temperature and the baryon load in it.Comment: 4 pages, two column text, To be published in Phys. Rev.

Oscillation tomografy study of Earth's composition and density with atmospheric neutrinos

Knowledge of the composition of the Earth's interior is highly relevant to many geophysical and geochemical problems. Neutrino oscillations are modified in a non-trivial way by the matter effects and can provide valuable and unique information not only on the density but also on the chemical and isotopic composition of the deep regions of the planet. In this paper, we re-examine the possibility of performing an oscillation tomography of the Earth with atmospheric neutrinos and antineutrinos to obtain information on the composition and density of the outer core and the mantle, complementary to that obtained by geophysical methods. Particular attention is paid to the D$^{\prime \prime}$ layer just above the core-mantle boundary and to the water (hydrogen) content in the mantle transition zone. Our analysis is based on a Monte-Carlo simulation of the energy and azimuthal angle distribution of $\mu$-like events generated by neutrinos. Taking as reference a model of the Earth consisting of 55 concentric layers with constant densities determined from the PREM, we evaluate the effect on the number of events due to changes in the composition and density of the outer core and the mantle. To examine the capacity of a detector like ORCA to resolve such variations, we construct regions in planes of two of these quantities where the statistical significance of the discrepancies between the reference and the modified Earth are less than $1\sigma$. The variations are implemented in such a way that the constraint imposed by both the total mass of the Earth and its moment of inertia are verified.Comment: Already published in the European Physical Journal

Cherenkov radiation by massless neutrinos

Due to their weak interactions, neutrinos can polarize a medium and acquire an induced charge. We consider the Cherenkov radiation emitted by neutrinos due to their effective electromagnetic interactions as they pass through a polarizable medium. The effect exists even for massless, chiral neutrinos, where no physics beyond the standard model needs to be assumed.Comment: 11 pages Latex file; to appear in Phys. Lett.

Earth tomography with atmospheric neutrino oscillations

The study of the flux of atmospheric neutrino crossing the Earth can provide useful information not only on the matter density of the different layers that make up the planet but also on their chemical composition. The key phenomenon that makes this possible is flavor oscillations and their dependence on the electron density along the neutrino baseline. To extract the relevant information, we simulate the energy and azimuth angle distribution of events produced in a generic neutrino telescope by atmospheric neutrinos passing through the deepest parts of the Earth. Changes in the densities of the outer core and the mantle are implemented by varying the location of the boundary between these layers so that the restrictions on the mass of and the moment of inertia of the Earth are both satisfied. This allows us to examine the effect of simultaneous changes in composition and density of the outer core, unlikely other works on the subject, where only one of these quantities was varied.Fil: D'Olivo, Juan Carlos. Universidad Nacional Autónoma de México. Instituto de Ciencias Nucleares; MéxicoFil: Herrera Lara, José Arnulfo. Universidad Nacional Autónoma de México. Instituto de Ciencias Nucleares; MéxicoFil: Romero, Ismael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Físicas de Mar del Plata; ArgentinaFil: Sampayo, Oscar Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Físicas de Mar del Plata; ArgentinaFil: Zapata, Gabriel Damián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Físicas de Mar del Plata. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Físicas de Mar del Plata; Argentin

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO