48 research outputs found

    Supersymmetric deformations of F1-NS5-branes and their exact CFT description

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    We consider certain classes of operators in the exact conformal field theory SL(2,R) x SU(2) x U(1)^4 describing strings in an AdS(3) x S(3) x T4 geometry supported by Neveu--Schwarz 3-form fluxes. This background arises in the near-horizon limit of a system of NS5-branes wrapped on a 4-torus and F1-branes smeared on the 4-torus when both types of branes are located at the same point in their common transverse space. We find a class of operators that lead to spacetime supersymmetric deformations. It is remarkable that most of these operators are not chiral primary with respect to the N=2 superconformal algebra on the wordsheet. A subset of these worldsheet conformal field theory deformations admits an interpretation either as a geometric deformation of the brane system or as a deformation of the distribution of the F1-branes, viewed as smooth instantons, inside the wrapped NS5-brane worldvolume. The 2-dimensional conformal field theory, however, seems to lack operators corresponding to arbitrary NS5-brane deformations, in contrast to pure NS5-brane systems where all geometric deformations can be accounted for by chiral primary operators.Comment: 30+1 pages, 1 table; v2 minor changes, version to appear in JHE

    我国人力资源开发及教育对策研究

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    人力资源是一切资源中最重要的资源,在知识经济时代,人力资源在经济增长中越来越起到决定性的作用,人力资源开发的成败关系到一个国家未来综合国力及国际竞争实力的强弱。教育是人力资源开发的根本途径,是人力资源开发的核心和关键,教育的规模和质量直接影响到人力资源的数量与质量,关系到一国未来经济发展的潜力。本文的重点是探讨和研究我国人力资源开发与教育的对策。全文共分为四章,主要内容包括: 第一章主要对人力资源开发的理论基础进行概述。全章分为两节。第一节介绍舒尔茨的人力资本理论。本节重点介绍:人力资本与物质资本的涵义,指明人力资本与物质资本的区别;人力资本在经济发展中的地位和作用;人力资本投资内涵;人力资...学位:工商管理硕士院系专业:管理学院工商管理教育中心_工商管理硕士(MBA)学号:19971510

    The modification of the energy spectrum of charged particles by exotic open 4-smoothness via superstring theory

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    In this paper we present a model where the modified Landau-like levels of charged particles in a magnetic field are determined due to the modified smoothness of R4\mathbb{R}^{4} as underlying structure of the Minkowski spacetime. Then the standard smoothness of R4\mathbb{R}^{4} is shifted to the exotic Rk4\mathbb{R}_{k}^{4}, k=2pk=2p, p=1,2...p=1,2.... This is achieved by superstring theory using gravitational backreaction induced from a strong, almost constant magnetic field on standard R4\mathbb{R}^{4}. The exact string background containing flat R4\mathbb{R}^{4} is replaced consistently by the curved geometry of SU(2)k×RSU(2)_{k}\times\mathbb{R} as part of the modified exact backgrounds. This corresponds to the change of smoothness on R4\mathbb{R}^{4} from the standard R4\mathbb{R}^{4} to some exotic Rk4\mathbb{R}_{k}^{4}. The calculations of the spectra are using the CFT marginal deformations and Wess-Zumino-Witten (WZW) models. The marginal deformations capture the effects of the magnetic field as well as its gravitational backreactions. The spectra depend on even level kk of WZW on SU(2). At the same time the WZ term as element of H3(SU(2),R)H^{3}(SU(2),\mathbb{R}) determines also the exotic smooth Rk4\mathbb{R}_{k}^{4}. As the consequence we obtain a non-zero mass-gap emerges in the spectrum induced from the presence of an exotic Rk4\mathbb{R}_{k}^{4}.Comment: 11 pages, Revtex4-1, will appear IJGMMP Vol. 50(1), 201

    Symplectic structure of N=1 supergravity with anomalies and Chern-Simons terms

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    The general actions of matter-coupled N=1 supergravity have Peccei-Quinn terms that may violate gauge and supersymmetry invariance. In addition, N=1 supergravity with vector multiplets may also contain generalized Chern-Simons terms. These have often been neglected in the literature despite their importance for gauge and supersymmetry invariance. We clarify the interplay of Peccei-Quinn terms, generalized Chern-Simons terms and quantum anomalies in the context of N=1 supergravity and exhibit conditions that have to be satisfied for their mutual consistency. This extension of the previously known N=1 matter-coupled supergravity actions follows naturally from the embedding of the gauge group into the group of symplectic duality transformations. Our results regarding this extension provide the supersymmetric framework for studies of string compactifications with axionic shift symmetries, generalized Chern-Simons terms and quantum anomalies.Comment: 27 pages; v2: typos corrected; version to be published in Class.Quantum Gra

    Supersymmetric AdS_5 solutions of M-theory

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    We analyse the most general supersymmetric solutions of D=11 supergravity consisting of a warped product of five-dimensional anti-de-Sitter space with a six-dimensional Riemannian space M_6, with four-form flux on M_6. We show that M_6 is partly specified by a one-parameter family of four-dimensional Kahler metrics. We find a large family of new explicit regular solutions where M_6 is a compact, complex manifold which is topologically a two-sphere bundle over a four-dimensional base, where the latter is either (i) Kahler-Einstein with positive curvature, or (ii) a product of two constant-curvature Riemann surfaces. After dimensional reduction and T-duality, some solutions in the second class are related to a new family of Sasaki-Einstein spaces which includes T^{1,1}/Z_2. Our general analysis also covers warped products of five-dimensional Minkowski space with a six-dimensional Riemannian space.Comment: 40 pages. v2: minor changes, eqs. (2.22) and (D.12) correcte

    Supersymmetric moduli of the SU(2) × linear dilaton background and NS5-branes

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    We study several classes of marginal deformations of the conformal field theory SU(2) x R. This theory describes the near-horizon region of a stack of parallel and coincident NS5-branes and is related holographically to little string theory. We investigate the supersymmetry properties of these deformations and we elucidate their role in the context of holography. The conformal field theory moduli space contains "non-holographic" operators that do not seem to have a simple interpretation in little string theory. Subsequently, we analyze several NS5-brane configurations in terms of SU(2) x R deformations. We discuss in detail interesting phenomena, like the excision of the strong coupling region associated with the linear dilaton and the manifestation of the symmetries of an NS5-brane setup in the deforming operators. Finally, we present a class of conformally hyperkaehler geometries that arise as "non-holographic" deformations of SU(2) x R
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