625 research outputs found

    CP-odd static electromagnetic properties of the W gauge boson and the t quark via the anomalous tbW coupling

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    In the framework of the electroweak chiral Lagrangian, the one-loop induced effects of the anomalous tbWtbW coupling, which includes both left- and right-handed complex components, on the static electromagnetic properties of the WW boson and the tt quark are studied. The attention is focused mainly on the CP-violating electromagnetic properties. It is found that the tbWtbW anomalous coupling can induce both CP-violating moments of the WW boson, namely, its electric dipole (μ~W\tilde{\mu}_W) and magnetic quadrupole (Q~W\tilde{Q}_W) moments. As far as the tt quark is concerned, a potentially large electric dipole moment (dt)(d_t) can arise due to the anomalous tbWtbW coupling. The most recent bounds on the left- and right-handed parameters from BB meson physics lead to the following estimates μ~W 10231022\tilde{\mu}_W ~ 10^{-23}-10^{-22} e-cm and Q~W 10381037\tilde{Q}_W~ 10^{-38}-10^{-37} e-cm2^2, which are 7 and 14 orders of magnitude larger than the standard model (SM) predictions, whereas dtd_t may be as large as 102210^{-22} e-cm, which is about 8 orders of magnitude larger than its SM counterpart.Comment: This paper has been merged with hep-ph/0612171 for publication in Physical Review

    Two-dimensional Quantum Black Holes, Branes in BTZ and Holography

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    We solve semiclassical Einstein equations in two dimensions with a massive source and we find a static, thermodynamically stable, quantum black hole solution in the Hartle-Hawking vacuum state. We then study the black hole geometry generated by a boundary mass sitting on a non-zero tension 1-brane embedded in a three-dimensional BTZ black hole. We show that the two geometries coincide and we extract, using holographic relations, information about the CFT living on the 1-brane. Finally, we show that the quantum black hole has the same temperature of the bulk BTZ, as expected from the holographic principle.Comment: 10 pages, 2 figures, RevTex, ``point particle of mass \mu '' changed with ``massive boundary source'' for better clarity. Action in (50) written in Z_2 symmetric form. Appendix clarified. Minor corrections and references added. Version accepted for pubblication in PRD15 (2006

    Electrochemical Characterization and CO2 Reduction Reaction of a Family of Pyridazine-Bridged Dinuclear Mn(I) Carbonyl Complexes

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    Three recently synthesized neutral dinuclear carbonyl manganese complexes with the pyridazine bridging ligand, of general formula [Mn2(μ-ER)2(CO)6(μ-pydz)] (pydz = pyridazine; E = O or S; R = methyl or phenyl), have been investigated by cyclic voltammetry in dimethylformamide and acetonitrile both under an inert argon atmosphere and in the presence of carbon dioxide. This family of Mn(I) compounds behaves interestingly at negative potentials in the presence of CO2. Based on this behavior, which is herein discussed, a rather efficient catalytic mechanism for the CO2 reduction reaction toward the generation of CO has been hypothesized

    Casimir-like tunneling-induced electronic forces

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    We study the quantum forces that act between two nearby conductors due to electronic tunneling. We derive an expression for these forces by calculating the flux of momentum arising from the overlap of evanescent electronic fields. Our result is written in terms of the electronic reflection amplitudes of the conductors and it has the same structure as Lifshitz's formula for the electromagnetically mediated Casimir forces. We evaluate the tunneling force between two semiinfinite conductors and between two thin films separated by an insulating gap. We discuss some applications of our results.Comment: 8 pages, 3 figs, submitted to Proc. of QFEXT'05, to be published in J. Phys.

    Influência da aplicação de Glyphosate na queda de frutos e de folhas de coqueiros.

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    O objetivo deste trabalho foi avaliar a queda de frutos e de folhas de coqueiros após a aplicação do herbicida glyphosate. O experimento foi instalado no município de Neópolis-SE, no período de agosto a setembro de 2007. O coqueiral da variedade Anão- Verde foi implantado há 11 anos, em área sob sistema de irrigação por microaspersão. O delineamento experimental foi o inteiramente casualizado, com cinco repetições, em esquema fatorial 3 x 3 + 1, sendo três doses do herbicida glyphosate (3,4; 6,8; e 13,6 g por planta), três formas de aplicação (produto aplicado apenas no estipe, da base a 1 m de altura; produto aplicado apenas no solo ao redor da copa, dentro de um raio de 2 m na zona de coroamento; e, ainda, a combinação das duas formas de aplicação), mais um tratamento adicional de controle sem aplicação. Durante quatro semanas, aos 7, 14, 21 e 28 dias após a aplicação dos tratamentos (DAA), realizou-se a contagem dos frutos caídos dos cachos de números 11, 12, 13, 14, 15, 16, 17, 18 e 19 e das folhas caídas. Aos 35 DAA, realizou-se a contagem dos frutos dos cachos 18 e 19 que possuíam valor comercial. Até os 28 DAA, o herbicida glyphosate não influenciou a queda de frutos e de folhas, independentemente da forma de aplicação, não havendo efeito desse herbicida sobre o número de frutos comerciais da colheita seguinte à aplicação

    Sistemas de produção: conceitos e definições no contexto agrícola.

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    Introdução. Definições e exemplificações de sistemas: Sistema de cultivo, Sistema de produção, Sistema em monocultura ou produção isolada; Sistema em sucessão de culturas; Sistema em consorciação de culturas ou policultivo; Sistema em integração: lavoura-pecuária, lavoura-floresta, pecuária-floresta, lavoura-pecuária-floresta. Ausência de interação. Interação entre sistemas de cultivo/criação conduzidos em diferentes áreas físicas. Interação entre sistemas de cultivo/criação conduzidos em um mesmo espaço físico. Sistema agrícola: sistema de sucessão soja - milho/trigo em SPD na região de Londrina-PR; sistema de sucessão soja - milho/sorgo em SPD na região de Rio Verde-GO; sistema de rotação soja-trigo (ano 1); soja-aveia ou nabo forrageiro (ano 2); milho-nabo forrageiro-trigo (ano 3); e soja-aveia (ano 4), em SPD na região de Passo Fundo-RS. sistema de sucessão soja ? milho/algodão em SPD na região de Sapezal-MT; sistema de sucessão soja - girassol/sorgo em SPD na região de Campo Novo do Parecis-MT; sistema de integração arroz irrigado-azevém para pastejo, na região de Pelotas-RS. sistema de sucessão de cana-de-açúcar com cultivo de amendoim durante o período de reforma do canavial na região de Sertãozinho-SP. sistema de sucessão de cana-de-açúcar com cultivo de Crotalaria spectabilis durante o período de reforma do canavial na região de Coruripe-AL. Bioma. Considerações finais.bitstream/item/69333/1/Doc-335-OL.pd

    The Spectral Energy Distribution of Powerful Starburst Galaxies I: Modelling the Radio Continuum

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    We have acquired radio continuum data between 70\,MHz and 48\,GHz for a sample of 19 southern starburst galaxies at moderate redshifts (0.067<z<0.2270.067 < z < 0.227) with the aim of separating synchrotron and free-free emission components. Using a Bayesian framework we find the radio continuum is rarely characterised well by a single power law, instead often exhibiting low frequency turnovers below 500\,MHz, steepening at mid-to-high frequencies, and a flattening at high frequencies where free-free emission begins to dominate over the synchrotron emission. These higher order curvature components may be attributed to free-free absorption across multiple regions of star formation with varying optical depths. The decomposed synchrotron and free-free emission components in our sample of galaxies form strong correlations with the total-infrared bolometric luminosities. Finally, we find that without accounting for free-free absorption with turnovers between 90 to 500\,MHz the radio-continuum at low frequency (ν<200\nu < 200\,MHz) could be overestimated by upwards of a factor of twelve if a simple power law extrapolation is used from higher frequencies. The mean synchrotron spectral index of our sample is constrained to be α=1.06\alpha=-1.06, which is steeper then the canonical value of 0.8-0.8 for normal galaxies. We suggest this may be caused by an intrinsically steeper cosmic ray distribution

    The Spectral Energy Distribution of Powerful Starburst Galaxies I : Modelling the Radio Continuum

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    This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.We have acquired radio-continuum data between 70MHz and 48 GHz for a sample of 19 southern starburst galaxies at moderate redshifts (0.067 < z < 0.227) with the aim of separating synchrotron and free-free emission components. Using a Bayesian framework, we find the radio continuum is rarely characterized well by a single power law, instead often exhibiting lowfrequency turnovers below 500 MHz, steepening at mid to high frequencies, and a flattening at high frequencies where free-free emission begins to dominate over the synchrotron emission. These higher order curvature components may be attributed to free-free absorption across multiple regions of star formation with varying optical depths. The decomposed synchrotron and free-free emission components in our sample of galaxies form strong correlations with the total-infrared bolometric luminosities. Finally, we find that without accounting for free-free absorption with turnovers between 90 and 500MHz the radio continuum at low frequency (v < 200 MHz) could be overestimated by upwards of a factor of 12 if a simple power-law extrapolation is used from higher frequencies. The mean synchrotron spectral index of our sample is constrained to be α = -1.06, which is steeper than the canonical value of -0.8 for normal galaxies. We suggest this may be caused by an intrinsically steeper cosmic ray distribution.Peer reviewe
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