The electromagnetic vertex of neutrinos in an electron background and a magnetic field

We study the electromagnetic vertex function of a neutrino that propagates in an electron background in the presence of a static magnetic field. The structure of the vertex function under the stated conditions is determined and it is written down in terms of a minimal and complete set of tensors. The one-loop expressions for all the form factors is given, up to terms that are linear in the magnetic field, and the approximate integral formulas that hold in the long wavelength limit are obtained. We discuss the physical interpretation of some of the form factors and their relation with the concept of the neutrino induced charge. The neutrino acquires a longitudinal and a transverse charge, due to the fact that the form factors depend on the transverse and longitudinal components of the photon momentum independently. We compute those form factors explicitly in various limiting cases and find that the longitudinal and transverse charge are the same for the case of a non-relativistic electron gas, but not otherwise.Comment: 18 pages. Revtex4, axodra

Gravitational coupling of neutrinos in a medium

In a medium that contains electrons but not the other charged leptons, such as normal matter, the gravitational interactions of neutrinos are not the same for all the neutrino flavors. We calculate the leading order matter-induced corrections to the neutrino gravitational interactions in such a medium and consider some of their physical implications.Comment: 21 pages, Latex, uses axodraw.sty (typos corrected; two references added. To appear in Phys. Rev. D

Possible astrophysical clues of dark matter

The physics of the supernova may provide a clue of the cosmological dark matter. In the absence of new physics, the supernova calculations do not explain the observed velocities of pulsars. However, if there exists a singlet fermion with mass in the 1-20 keV range and a small mixing with neutrinos, this particle could be emitted asymmetrically from a cooling neutron star in the event of a supernova explosion. The asymmetry could explain the long-standing puzzle of pulsar velocities. The same particle could be the dark matter. Observations of X-ray telescopes, as well as a future detection of gravitational waves from a nearby supernova can confirm or rule out this possibility.Comment: 6 pages, 1 figure; talk presented at the 6th UCLA Symposium on Sources and Detection of Dark Matter and Dark Energy in the Universe (Dark Matter 2004), Marina del Rey, California, February 18-20, 200

Axial vector current in an electromagnetic field and low-energy neutrino-photon interactions

An expression for the axial vector current in a strong, slowly varying electromagnetic field is obtained. We apply this expression to the construction of the effective action for low-energy neutrino-photon interactions.Comment: 6 pages, references updated, final version to appear in Phys. Rev.

Electromagnetic properties of a neutrino stream

In a medium that contains a neutrino background in addition to the matter particles, the neutrinos contribute to the photon self-energy as a result of the effective electromagnetic vertex that they acquire in the presence of matter. We calculate the contribution to the photon self-energy in a dense plasma, due to the presence of a gas of charged particles, or neutrinos, that moves as a whole relative to the plasma. General formulas for the transverse and longitudinal components of the photon polarization tensor are obtained in terms of the momentum distribution functions of the particles in the medium, and explicit results are given for various limiting cases of practical interest. The formulas are used to study the electromagnetic properties of a plasma that contains a beam of neutrinos. The transverse and longitudinal photon dispersion relations are studied in some detail. Our results do not support the idea that neutrino streaming instabilities can develop in such a system. We also indicate how the phenomenon of optical activity of the neutrino gas is modified due to the velocity of the neutrino background relative to the plasma. The general approach and results can be adapted to similar problems involving relativistic plasmas and high-temperature gauge theories in other environments.Comment: Revtex, 19 pages and 3 included ps file

Nucleon contribution to the neutrino electromagnetic vertex in matter

We calculate the nucleon contribution to the electromagnetic vertex of a neutrino in a background of particles, including the effect of the anomalous magnetic moment of the nucleons. Explicit formulas for the form factors are given in various physical limits of practical interest. Several applications of the results are mentioned, including the effect of an external magnetic field on the dispersion relation of a neutrino in matter.Comment: LaTeX, 18 pages; to appear in PR

Flavor coupled with chiral oscillations in the presence of an external magnetic field

By reporting to the Dirac wave-packet prescription where it is formally assumed the {\em fermionic} nature of the particles, we shall demonstrate that chiral oscillations implicitly aggregated to the interference between positive and negative frequency components of mass-eigenstate wave-packets introduce some small modifications to the standard neutrino flavor conversion formula. Assuming the correspondent spinorial solutions of a ``modified'' Dirac equation, we are specifically interested in quantifying flavor coupled with chiral oscillations for a {\em fermionic} Dirac-{\em type} particle (neutrino) non-minimally coupling with an external magnetic field {\boldmath$B$}. The viability of the intermediate wave-packet treatment becomes clear when we assume {\boldmath$B$} orthogonal/parallel to the direction of the propagating particle.Comment: 21 page

Prevención de lavado de activos y su impacto en las compañías de seguro en nuestro país

Trabajo final de posgrado (Especialización en Contabilidad Superior y Auditoría)El objetivo del presente trabajo fue analizar la problemática del lavado de activos, las medidas tomadas a nivel nacional e internacional para combatirlo y el impacto que han tenido sobre las actividades de seguros en nuestro país. Del análisis de los resultados surge que el lavado de activos es un flagelo que afecta significativamente a toda la comunidad internacional debido a los efectos nocivos que provoca en los sistemas económicos, políticos y sociales. Esto produjo la necesidad de crear organismos internacionales a fin de establecer medidas de protección efectivas para los países afectados. En el ámbito nacional la normativa comenzó a tener mayor relevancia a partir de la sanción de la norma legal de fondo (Ley Nº 25.246). En la misma se diseñó un sistema de prevención de lavado de activos y financiación del terrorismo (LA/FT), llevado a cabo a través de un régimen penal administrativo, la creación de un organismo de control y la imposición de obligaciones a determinados sujetos. El mercado asegurador es uno de los destinos elegidos por los criminales para llevar a cabo operaciones de lavado. Es por ello que se adoptó una serie de normativas específicas para este tipo de entes, las cuales han impactado significativamente en la operatoria de los mismos debido a la necesidad de adecuar las estructuras formales y administrativas de su funcionamiento a fin de cumplimentar con dichas normativas.Fil: D’olivo, Santiago. Universidad Nacional de Córdoba. Facultad de Ciencias Económicas; Argentina