109 resultados para Quantização BRST


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Pós-graduação em Física - IFT

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In this work we review the basic principles of the theory of the relativistic bosonic string through the study of the action functionals of Nambu-Goto and Polyakov and the techniques required for their canonical, light-cone, and path-integral quantisation. For this purpose, we briefly review the main properties of the gauge symmetries and conformal field theory involved in the techniques studied.

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We study the Becchi-Rouet-Stora-Tyutin (BRST) structure of a self-interacting antisymmetric tensor gauge field, which has an on-shell null-vector gauge transformation. The Batalin-Vilkovisky covariant general formalism is briefly reviewed, and the issue of on-shell nilpotency of the BRST transformation is elucidated. We establish the connection between the covariant and the canonical BRST formalisms for our particular theory. Finally, we point out the similarities and differences with Wittens string field theory.

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The propagator of a relativistic spinning particle is calculated using the Becchi-Rouet-Stora-Tyutin-(BRST)-invariant path-integral formalism of Fradkin and Vilkovisky. The spinless case is considered as an introduction to the formalism.

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Syftet med denna studie var att beskriva bröstcancerdrabbade kvinnors upplevelser av diagnos och förlust av bröst till följd av bröstcancerkirurgi. Vidare var syftet att beskriva vilka copingstrategier kvinnorna använde.Studien genomfördes som en litteraturstudie. Litteratur söktes i databasen Cinahl samt i informationstjänsten ELIN. Underlaget för denna studie är 19 artiklar av kvalitativ ansats. Resultatet visade att bröstcancerbeskedet var en chockerande upplevelse för kvinnor. Diagnosen framkallade ångest, rädsla och kom oftast som en överraskning. Bröstförlusten orsakade mycket lidande för kvinnorna i form av förlorad kvinnlighet, kroppsbild, förändrad sexualitet och förändrade relationer. Kvinnorna kände sig fula, vanställda och deformerade. Det framkom också att kvinnorna ville skyla sin bröstförlust för sig själv och andra. De isolerade sig från omgivningen. Kvinnor som genomgått rekonstruktion beskrev en känsla av att åter få känna sig normala. De copingstrategier som kvinnorna använde var att acceptera sin situation, viljan att leva, positivt tänkande, leva som vanligt, stöd av närstående, religion samt vara aktiva i sin behandling av sjukdomen. Genom att sjuksköterskan söker evidens och vetenskapligt beprövad information om sjukdom och hur den påverkar kvinnors liv så kan sjuksköterskan på ett bra sätt hjälpa kvinnor att förstå och acceptera det som sker, ge stöd och lindra lidande.

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We show that the BRST charge for the N = 2 superstring system can be written as Q = e(-R)(phi dz/2 pi ib gamma(+)gamma(-))e(R), when b and gamma(+/-) are super-reparametrizations ghosts. This provides a trivial proof of the nilpotence of this operator. (C) 2000 Published by Elsevier B.V. B.V. All rights reserved.

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In a previous Letter. The BRST cohomology in the pure spinor formalism of the superstring was shown to coincide with the light-cone Green-Schwarz spectrum by using an SO(8) parameterization of the pure spinor. In this Letter, the SO(9, 1) Lorentz generators are explicitly constructed using this SO(8) parameterization, proving the Lorentz invariance of the pure spinor BRST cohomology. (C) 2001 Published by Elsevier B.V. B.V.

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We derive the Wess-Zumino scalar term of the generalized Schwinger model both in the singular and nonsingular cases by using BRST-BFV framework. The photon propagators are also computed in the extended Lorentz gauge.

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We write the BRST operator of the N = 1 superstring as, Q = e-R(1/2πiφdzγ2b)eR where y and b are super-reparameterization ghosts. This provides a trivial proof that Q is nilpotent. © 1999 Published by Elsevier Science B.V. All rights reserved.

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A relation is found between nonlocal conserved charges in string theory and certain ghost-number two states in the BRST cohomology. This provides a simple proof that the nonlocal conserved charges for the superstring in an AdS 5 × S5 background are BRST-invariant in the pure spinor formalism and are κ-symmetric in the Green-Schwarz formalism. © SISSA/ISAS 2005.

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In the study of the Type II superstring, it is useful to consider the BRST complex associated to the sum of two pure spinors. The cohomology of this complex is an infinite-dimensional vector space. It is also a finite-dimensional algebra over the algebra of functions of a single pure spinor. In this paper we study the multiplicative structure. © 2013 World Scientific Publishing Company.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Pós-graduação em Física - IFT

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Pós-graduação em Física - IFT

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Fazemos a quantização canônica do campo vetorial massivo, primeiro com relação a observadores inerciais e depois com relação a observadores acelerados. Investigamos como uma fonte uniformemente acelerada em Minkowski interage com o campo vetorial massivo no vácuo inercial, através do cálculo da taxa de resposta total. Esta taxa de resposta é calculada em dois referenciais diferentes, um inercial e outro co-acelerado com a fonte. De acordo com o efeito Unruh, no referencial acelerado, o vácuo inercial corresponde a um banho térmico de partículas. Levando em conta este efeito, mostramos, explicitamente, que estas taxas de resposta são idênticas. Este resultado pode ser usado para descrever a interação de elétrons estáticos com partículas Z0 presentes na radiação Hawking, desde que os elétrons estejam muito próximos do horizonte de eventos de um buraco negro.