Some remarks on the spectral functions of the Abelian Higgs Model

We consider the unitary Abelian Higgs model and investigate its spectral functions at one-loop order. This analysis allows to disentangle what is physical and what is not at the level of the elementary particle propagators, in conjunction with the Nielsen identities. We highlight the role of the tadpole graphs and the gauge choices to get sensible results. We also introduce an Abelian Curci-Ferrari action coupled to a scalar field to model a massive photon which, like the non-Abelian Curci-Ferarri model, is left invariant by a modified non-nilpotent BRST symmetry. We clearly illustrate its non-unitary nature directly from the spectral function viewpoint. This provides a functional analogue of the Ojima observation in the canonical formalism: there are ghost states with nonzero norm in the BRST-invariant states of the Curci-Ferrari model.Comment: 32 pages, 12 figure

Aspectos econômicos, ambientais e sociais da produção cafeeira em diferentes sistemas em Rondônia.

Este trabalho procurou avaliar o desempenho econômico, ambiental e social de diferentes sistemas de produção de café no estado de Rondônia. Foram selecionados cinco sistemas de produção de café em três importantes municípios produtores de café no estado de Rondônia: Alta Floresta, Cacoal e Nova Brasilândia.bitstream/CPAF-RO-2010/14572/1/351-cafeicultura.pd

Theory for phonon pumping by magnonic spin currents

In recent years several experimental observations and theoretical predictions of unique phenomena involving the interplay between spin currents and the coupled magnetization-elastic dynamics have invigorated the field of spintronics. One important experiment reported several years ago showed that elastic waves can produce spin pumping, that is, generation of spin currents in a metallic film in contact with a ferromagnetic material. Very recently the Onsager reciprocal of this effect has been observed in samples made of a film of the insulating ferrimagnet yttrium iron garnet in contact with a platinum strip with nanoscopic silver particles that is known to exhibit a giant spin Hall effect. By passing an electric current through the metallic strip, the spin current generated by the spin Hall effect produces a large magnonic spin current that excites phonons with microwave frequency, observed by Brillouin light scattering. Here we show that these experiments are explained by a theory based on a process in which one magnon in the spin current creates one phonon and another magnon, with conservation of energy and momentum. The theoretical value of the critical charge current in the metallic strip necessary to drive phonons and the values of the phonon frequencies are in good agreement with the values measured experimentally

Random magnetic fields inducing solar neutrino spin-flavor precession in a three generation context

We study the effect of random magnetic fields in the spin-flavor precession of solar neutrinos in a three generation context, when a non-vanishing transition magnetic moment is assumed. While this kind of precession is strongly constrained when the magnetic moment involves the first family, such constraints do not apply if we suppose a transition magnetic moment between the second and third families. In this scenario we can have a large non-electron anti-neutrino flux arriving on Earth, which can lead to some interesting phenomenological consequences, as, for instance, the suppression of day-night asymmetry. We have analyzed the high energy solar neutrino data and the KamLAND experiment to constrain the solar mixing angle, and solar mass difference, and we have found a larger shift of allowed values.Comment: 10 pages, 3 figure

Purificação e caracterização parcial de uma toxina protéica presente na alga Vidalia obtusiloba (Mertens ex C. Agardh) J. Agardh.

Coleta e armazenagem de algas ; Preparação do extrato total e da fração 0/60 (F0/60); Determinação de proteínas; Atividade hemaglutinante; Atividade inibidora de tripsina; Atividade tóxica; Termoestabilidade das atividades hemaglutinantes e tóxicas; Cromatografia de troca iônica em coluna de DEAE-Sephacel; Cromatografia de interação hidrofóbica em coluna de Phenyl-Sepharose CL-4B; Cromatografia de exclusão molecular em coluna de superose -1 2 HR acoplada ao sistema de FPLC; Eletroforese em gel de poliacrilamida.bitstream/item/36601/1/Doc72.pd

Eu2+ spin dynamics in the filled skutterudites EuM4Sb12 (M = Fe, Ru, Os)

We report evidence for a close relation between the thermal activation of the rattling motion of the filler guest atoms, and inhomogeneous spin dynamics of the Eu2+ spins. The spin dynamics is probed directly by means of Eu2+ electron spin resonance (ESR), performed in both X-band (9.4 GHz) and Q-band (34 GHz) frequencies in the temperature interval 4.2 < T < 300 K. A comparative study with ESR measurements on the Beta-Eu8Ga16Ge30 clathrate compound is presented. Our results point to a correlation between the rattling motion and the spin dynamics which may be relevant for the general understanding of the dynamics of cage systems.Comment: 6 pages, 4 figures, accepted for publication in Phys. Rev.