4 resultados para Termo topológico de Chern-Simons

em Biblioteca Digital da Produção Intelectual da Universidade de São Paulo


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By computing the two-loop effective potential of the D=3 N=1 supersymmetric Chern-Simons model minimally coupled to a massless self-interacting matter superfield, it is shown that supersymmetry is preserved, while the internal U(1) and the scale symmetries are broken at two-loop order, dynamically generating masses both for the gauge superfield and for the real component of the matter superfield.

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We study baryon asymmetry generation originated from the leptogenesis in the presence of hypermagnetic fields in the early Universe plasma before the electroweak phase I ransition (EWPT). For the simplest Chern-Simons (CS) wave configuration of hypermagnetic field we find the baryon asymmetry growth when the hypermagnetic field value changes due to alpha(2)-dynamo and the lepton asymmetry rises due to the Abelian anomaly. We solve the corresponding integro-differential equations for the lepton asymmetries describing such selfconsistent dynamics for lepto- and baryogenesis in the two scenarios: (i) when a primordial lepton asymmetry sits in right electrons e(R); and (ii) when, in addition to e(R), a left lepton asyninwtty for e(L) and v(eL) at due to chirality flip reactions provided by in Iiigg,s decays at the temperatures, T < T-RL similar to 10 TeV. We find that the baryon asymmetry of the Universe (BAU) rises very fast through such leptogenesis, especially, in strong hypermagnetic fields. Varying (decreasing) the CS wave number parameter k(0) < 10(-7) T-EW one can recover the observable value of BAU, eta(B) similar to 10(-9), where k(0) = 10(-7) T-EW corresponds to the ataxinittat value for CS wave number surviving ohmic dissipation of hypermagnetic field. In the scenario (ii) one predicts the essential difference of the lepton numbers of right- and left electrons at EWPT time, L-eR - L-eL similar to (mu(eR) / mu(eL))/T-EW = Delta mu/T-EW similar or equal to 10(-5) that can be used as an initial condition for chiral asymmetry after EWPT.

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We propose an integral formulation of the equations of motion of a large class of field theories which leads in a quite natural and direct way to the construction of conservation laws. The approach is based on generalized non-abelian Stokes theorems for p-form connections, and its appropriate mathematical language is that of loop spaces. The equations of motion are written as the equality of a hyper-volume ordered integral to a hyper-surface ordered integral on the border of that hyper-volume. The approach applies to integrable field theories in (1 + 1) dimensions, Chern-Simons theories in (2 + 1) dimensions, and non-abelian gauge theories in (2 + 1) and (3 + 1) dimensions. The results presented in this paper are relevant for the understanding of global properties of those theories. As a special byproduct we solve a long standing problem in (3 + 1)-dimensional Yang-Mills theory, namely the construction of conserved charges, valid for any solution, which are invariant under arbitrary gauge transformations. (C) 2012 Elsevier B.V. All rights reserved.

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A case-control study (2008-2009) analyzed risk factors for preterm birth in the city of Campina Grande, Paraíba State, Brazil. A total of 341 preterm births and 424 controls were included. A multiple logistic regression model was used. Risk factors for preterm birth were: previous history of preterm birth (OR = 2.32; 95%CI: 1.25-4.29), maternal age (OR = 2.00; 95%CI: 1.00-4.03), inadequate prenatal care (OR = 2.15; 95%CI: 1.40-3.27), inadequate maternal weight gain (OR = 2.33; 95%CI: 1.45-3.75), maternal physical injury (OR = 2.10; 95%CI: 1.22-3.60), hypertension with eclampsia (OR = 17.08; 95%CI: 3.67-79.43) and without eclampsia (OR = 6.42; 95%CI: 3.50-11.76), hospitalization (OR = 5.64; 95%CI: 3.47-9.15), altered amniotic fluid volume (OR = 2.28; 95%CI: 1.32-3.95), vaginal bleeding (OR = 1.54; 95%CI: 1.01-2.34), and multiple gestation (OR = 22.65; 95%CI: 6.22-82.46). High and homogeneous prevalence of poverty and low maternal schooling among both cases and controls may have contributed to the fact that socioeconomic variables did not remain significantly associated with preterm birth.