46,856 research outputs found

    Non-Abelian Gravity and Antisymmetric Tensor Gauge Theory

    Get PDF
    A non-abelian generalisation of a theory of gravity coupled to a 2-form gauge field and a dilaton is found, in which the metric and 3-form field strength are Lie algebra-valued. In the abelian limit, the curvature with torsion is self-dual in four dimensions, or has SU(n) holonomy in 2n2n dimensions. The coupling to self-dual Yang-Mills fields in 4 dimensions, or their higher dimensional generalisation, is discussed. The abelian theory is the effective action for (2,1) strings, and the non-abelian generalisation is relevant to the study of coincident branes in the (2,1) string approach to M-theory. The theory is local when expressed in terms of a vector pre-potential.Comment: 14 pages, phyzzx macro. Minor correction

    Actions For (2,1) Sigma-Models and Strings

    Get PDF
    Effective actions are derived for (2,0) and (2,1) superstrings by studying the corresponding sigma-models. The geometry is a generalisation of Kahler geometry involving torsion and the field equations imply that the curvature with torsion is self-dual in four dimensions, or has SU(n,m) holonomy in other dimensions. The Yang-Mills fields are self-dual in four dimensions and satisfy a form of the Uhlenbeck-Yau equation in higher dimensions. In four dimensions with Euclidean signature, there is a hyperkahler structure and the sigma-model has (4,1) supersymmetry, while for signature (2,2) there is a hypersymplectic structure consisting of a complex structure squaring to -1 and two real structures squaring to 1. The theory is invariant under a twisted form of the (4,1) superconformal algebra which includes an SL(2,R) Kac-Moody algebra instead of an SU(2) Kac-Moody algebra. Kahler and related geometries are generalised to ones involving real structures.Comment: 32 pages, phyzzx macr

    Geometry, Isometries and Gauging of (2,1) Heterotic Sigma-Models

    Get PDF
    The geometry of (2,1) supersymmetric sigma-models is reviewed and the conditions under which they have isometry symmetries are analysed. Certain potentials are constructed that play an important role in the gauging of such symmetries. The gauged action is found for a special class of models.Comment: 12 pages, LaTeX, no figures. Minor changes; version to appear in Physics Letters

    Sigma models with non-commuting complex structures and extended supersymmetry

    Get PDF
    We discuss additional supersymmetries for N = (2, 2) supersymmetric non-linear sigma models described by left and right semichiral superfields.Comment: 11 pages. Talk presented by U.L. at "30th Winter School on Geometry and Physics" Srni, Czech Republic January 2010

    Potentials for (p,0) and (1,1) supersymmetric sigma models with torsion

    Full text link
    Using (1,0) superfield methods, we determine the general scalar potential consistent with off-shell (p,0) supersymmetry and (1,1) supersymmetry in two-dimensional non-linear sigma models with torsion. We also present an extended superfield formulation of the (p,0) models and show how the (1,1) models can be obtained from the (1,1)-superspace formulation of the gauged, but massless, (1,1) sigma model.Comment: 11 page

    The Gauged (2,1) Heterotic Sigma-Model

    Get PDF
    The geometry of (2,1) supersymmetric sigma-models with isometry symmetries is discussed. The gauging of such symmetries in superspace is then studied. We find that the coupling to the (2,1) Yang-Mills supermultiplet can be achieved provided certain geometric conditions are satisfied. We construct the general gauged action, using an auxiliary vector to generate the full non-polynomial structure.Comment: LaTeX, 25 pages, no figures; version to appear in Nuclear Physics

    Hamiltonian construction of W-gravity actions

    Full text link
    We show that all W-gravity actions can be easilly constructed and understood from the point of view of the Hamiltonian formalism for the constrained systems. This formalism also gives a method of constructing gauge invariant actions for arbitrary conformally extended algebras.Comment: 9 page

    Flux Compactifications of String Theory on Twisted Tori

    Full text link
    Global aspects of Scherk-Schwarz dimensional reduction are discussed and it is shown that it can usually be viewed as arising from a compactification on the compact space obtained by identifying a (possibly non-compact) group manifold G under a discrete subgroup Gamma, followed by a truncation. This allows a generalisation of Scherk-Schwarz reductions to string theory or M-theory as compactifications on G/Gamma, but only in those cases in which there is a suitable discrete subgroup of G. We analyse such compactifications with flux and investigate the gauge symmetry and its spontaneous breaking. We discuss the covariance under O(d,d), where d is the dimension of the group G, and the relation to reductions with duality twists. The compactified theories promote a subgroup of the O(d,d) that would arise from a toroidal reduction to a gauge symmetry, and we discuss the interplay between the gauge symmetry and the O(d,d,Z) T-duality group, suggesting the role that T-duality should play in such compactifications.Comment: 43 page

    New Realisations of Minimal Models and the Structure of W-Strings

    Full text link
    The quantization of a free boson whose momentum satisfies a cubic constraint leads to a c=\ha conformal field theory with a BRST symmetry. The theory also has a WW_\infty symmetry in which all the generators except the stress-tensor are BRST-exact and so topological. The BRST cohomology includes states of conformal dimensions 0,\si,\ha, together with \lq copies' of these states obtained by acting with picture-changing and screening operators. The 3-point and 4-point correlation functions agree with those of the Ising model, suggesting that the theory is equivalent to the critical Ising model. At tree level, the W3W_3 string can be viewed as an ordinary c=26c=26 string whose conformal matter sector includes this realisation of the Ising model. The two-boson W3W_3 string is equivalent to the Ising model coupled to two-dimensional quantum gravity. Similar results apply for other W-strings and minimal models.Comment: 28 pages, NSF-ITP-93-65, QMW-93-1

    The gauge algebra of double field theory and Courant brackets

    Get PDF
    We investigate the symmetry algebra of the recently proposed field theory on a doubled torus that describes closed string modes on a torus with both momentum and winding. The gauge parameters are constrained fields on the doubled space and transform as vectors under T-duality. The gauge algebra defines a T-duality covariant bracket. For the case in which the parameters and fields are T-dual to ones that have momentum but no winding, we find the gauge transformations to all orders and show that the gauge algebra reduces to one obtained by Siegel. We show that the bracket for such restricted parameters is the Courant bracket. We explain how these algebras are realised as symmetries despite the failure of the Jacobi identity.Comment: 25 pages, LaTe
    corecore