970 resultados para QUARTERNARY CHIRAL CENTERS


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Chiral cosmic strings are naturally produced at the end of D-term inflation and they present very interesting cosmological consequences. In this work, we investigate the formation and evolution of wakes by a chiral string. We show that, for cold dark matter, the mechanism of forming wakes by a chiral string is similar to the mechanism by an ordinary string.

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Effective chiral Lagrangians involving constituent quarks, Goldstone bosons and long-distance gluons are believed to describe the strong interactions in an intermediate energy region between the confinement scale and the chiral symmetry breaking scale. Baryons and mesons in such a description are bound states of constituent quarks. We discuss the combined use of the techniques of effective chiral field theory and of the field theoretic method known as Fock-Tani representation to derive effective hadron interactions. The Fock-Tani method is based on a change of representation by means of a unitary transformation such that the composite hadrons are redescribed by elementary-particle field operators. Application of the unitary transformation on the microscopic quark-quark interaction derived from a chiral effective Lagrangian leads to chiral effective interactions describing all possible processes involving hadrons and their constituents. The formalism is illustrated by deriving the one-pion-exchange potential between two nucleons using the quark-gluon effective chiral Lagrangian of Manohar and Georgi. We also present the results of a study of the saturation properties of nuclear matter using this formalism.

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Chiral symmetry breaking at finite baryon density is usually discussed in the context of quark matter, i.e. a system of deconfined quarks. Many systems like stable nuclei and neutron stars however have quarks confined within nucleons. In this paper we construct a Fermi sea of three-quark nucleon clusters and investigate the change of the quark condensate as a function of baryon density. We study the effect of quark clustering on the in-medium quark condensate and compare results with the traditional approach of modeling hadronic matter in terms of a Fermi sea of deconfined quarks.

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Chiral-symmetry restoration is usually discussed in the context of quark matter, a system of deconfined quarks. However, many systems like stable nuclei and neutron stars have quarks confined within nucleons. In the present paper we use a Fermi sea of three-quark clusters instead of a Fermi sea of deconfined quarks to investigate the in-medium quark condensate. We find that an enhancement of the chiral breaking in clustered matter as claimed in the literature is not a consequence of the clustering but rather dependent on the microscopic model dynamics.

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In this work, we study the influence of the way pious couple to nucleons in perturbative calculation of an observable in the pion-nucleon scattering.

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We present the higgsing of three-dimensional N = 6 superconformal ABJM type theories coupled to conformal supergravity, so called topologically gauged ABJM theory, thus providing a gravitational extension of previous work on the relation between N M2 and N D2-branes. The resulting N = 6 supergravity theory appears at a chiral point similar to that of three-dimensional chiral gravity introduced recently by Li, Song and Strominger, but with the opposite sign for the Ricci scalar term in the lagrangian. We identify the supersymmetry in the broken phase as a particular linear combination of the supersymmetry and special conformal supersymmetry in the original topologically gauged ABJM theory. We also discuss the higgsing procedure in detail paying special attention to the role played by the U(1) factors in the original ABJM model and the U(1) introduced in the topological gauging.

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We include the Roper excitation of the nucleon in a version of heavy-baryon chiral perturbation theory recently developed for energies around the delta resonance. We find significant improvement in the P(11) channel. (C) 2011 Elsevier B.V. All rights reserved.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The time evolution of the matter produced in high energy heavy-ion collisions seems to be well described by relativistic viscous hydrodynamics. In addition to the hydrodynamic degrees of freedom related to energy-momentum conservation, degrees of freedom associated with order parameters of broken continuous symmetries must be considered because they are all coupled to each other. of particular interest is the coupling of degrees of freedom associated with the chiral symmetry of QCD. Quantum and thermal fluctuations of the chiral fields act as noise sources in the classical equations of motion, turning them into stochastic differential equations in the form of Ginzburg-Landau-Langevin (GLL) equations. Analytic solutions of GLL equations are attainable only in very special circumstances and extensive numerical simulations are necessary, usually by discretizing the equations on a spatial lattice. However, a not much appreciated issue in the numerical simulations of GLL equations is that ultraviolet divergences in the form of lattice-spacing dependence plague the solutions. The divergences are related to the well-known Rayleigh-Jeans catastrophe in classical field theory. In the present communication we present a systematic lattice renormalization method to control the catastrophe. We discuss the implementation of the method for a GLL equation derived in the context of a model for the QCD chiral phase transition and consider the nonequilibrium evolution of the chiral condensate during the hydrodynamic flow of the quark-gluon plasma.

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Inspired by analytic results obtained for a systematic expansion of the memory kernel in dissipative quantum mechanics, we propose a phenomenological procedure to incorporate non-markovian corrections to the Langevin dynamics of an order parameter in field theory systematically. In this note, we restrict our analysis to the onset of the evolution. As an example, we consider the process of phase conversion in the chiral transition.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Estimou-se a prevalência e a incidência de parasitas intestinais em crianças e funcionários de 5 creches municipais em Botucatu/SP. Foram realizados dois estudos seccionais em 2002 (N=379) e 2003 (N=397) e um estudo longitudinal observacional, onde as crianças de 2002 e 2003 foram seguidas por um ano. Foram aplicados questionários nos funcionários e nos pais das crianças, onde foram coletadas as seguintes variáveis: nível sócio-econômico, hábitos sanitários, moradia, idade, sexo e presença de animais domésticos. Foram realizados exames coproparasitológicos nas crianças das creches. A prevalência de enteroparasitas em 2002 foi de 76,74% e 34% em 2003. As variáveis associadas à presença de enteroparasitas no ano de 2002 foram: localização das creches (OR=0,27 IC=0,15-0,47), renda familiar (OR=4,38 IC=1,91-10,04), sexo (OR=0,52 IC=0,32-0,85), faixa etária (OR=2,08 IC=1,06-4,08) e presença de animais domésticos na casa (OR=1,85 IC=1,10-3,11); em 2003, as variáveis foram: creche localizada em bairro periférico (OR=0,49 IC=0,31-0,78), renda familiar (OR=3,69 IC=2,19-6,24), nível educacional da mãe (OR=6,19 IC=1,81-21,21), sexo (OR=0,36 IC=0,36-0,93) e presença de animais domésticos (OR=1,68 IC=1,01-2,79). A coorte foi integrada por 253 crianças apresentando incidência de 23,22%. Os dados deste estudo evidenciam situações de risco em populações específicas (creches) e poderiam ser utilizados por Instituições que promovem o cuidado com as crianças.