7,451 research outputs found

    Closed Superstring in Noncommutative Compact Spacetime

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    In this paper we study the effects of noncommutativity on a closed superstring propagating in the spacetime that is compactified on tori. The effects of compactification and noncommutativity appear in the momentum, quantization, supercurrent, super-conformal generators and in the boundary state of the closed superstring emitted from a Dp_p-brane with the NS⊗\otimesNS background BB-field.Comment: 11 pages, Latex, no figur

    3D gauged supergravity from SU(2) reduction of N=1N=1 6D supergravity

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    We obtain Yang-Mills SU(2)×GSU(2)\times G gauged supergravity in three dimensions from SU(2)SU(2) group manifold reduction of (1,0) six dimensional supergravity coupled to an anti-symmetric tensor multiplet and gauge vector multiplets in the adjoint of GG. The reduced theory is consistently truncated to N=4N=4 3D supergravity coupled to 4(1+dim G)4(1+\textrm{dim}\, G) bosonic and 4(1+dim G)4(1+\textrm{dim}\, G) fermionic propagating degrees of freedom. This is in contrast to the reduction in which there are also massive vector fields. The scalar manifold is R×SO(3, dim G)SO(3)×SO(dim G)\mathbf{R}\times \frac{SO(3,\, \textrm{dim}\, G)}{SO(3)\times SO(\textrm{dim}\, G)}, and there is a SU(2)×GSU(2)\times G gauge group. We then construct N=4N=4 Chern-Simons (SO(3)⋉R3)×(G⋉RdimG)(SO(3)\ltimes \mathbf{R}^3)\times (G\ltimes \mathbf{R}^{\textrm{dim}G}) three dimensional gauged supergravity with scalar manifold SO(4, 1+dimG)SO(4)×SO(1+dimG)\frac{SO(4,\,1+\textrm{dim}G)}{SO(4)\times SO(1+\textrm{dim}G)} and explicitly show that this theory is on-shell equivalent to the Yang-Mills SO(3)×GSO(3)\times G gauged supergravity theory obtained from the SU(2)SU(2) reduction, after integrating out the scalars and gauge fields corresponding to the translational symmetries R3×Rdim G\mathbf{R}^3\times \mathbf{R}^{\textrm{dim}\, G}.Comment: 24 pages, no figures, references added and typos correcte

    On Subleading Contributions to the AdS/CFT Trace Anomaly

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    In the context of the AdS/CFT correspondence, we perform a direct computation in AdS_5 supergravity of the trace anomaly of a d=4, N=2 SCFT. We find agreement with the field theory result up to next to leading order in the 1/N expansion. In particular, the order N gravitational contribution to the anomaly is obtained from a Riemann tensor squared term in the 7-brane effective action deduced from heterotic - type I duality. We also discuss, in the AdS/CFT context, the order N corrections to the trace anomaly in d=4, N=4 SCFTs involving SO or Sp gauge groups.Comment: 25 pages, LaTeX, v2: references adde

    Duality Symmetries in N=2 Heterotic Superstring

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    We review the derivation and the basic properties of the perturbative prepotential in N=2 compactifications of the heterotic superstring. We discuss the structure of the perturbative monodromy group and the embedding of rigidly supersymmetric monodromies associated with enhanced gauge groups, at both perturbative and non-perturbative level.Comment: Based on talks presented at several conferences. 12 pages, LaTe

    Worldsheet Realization of the Refined Topological String

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    A worldsheet realization of the refined topological string is proposed in terms of physical string amplitudes that compute generalized N=2 F-terms of the form F_{g,n} W^{2g}Y^{2n} in the effective supergravity action. These terms involve the chiral Weyl superfield W and a superfield Y defined as an N=2 chiral projection of a particular anti-chiral T-bar vector multiplet. In Heterotic and Type I theories, obtained upon compactification on the six-dimensional manifold K3xT2, T is the usual K\"ahler modulus of the T2 torus. These amplitudes are computed exactly at the one-loop level in string theory. They are shown to reproduce the correct perturbative part of the Nekrasov partition function in the field theory limit when expanded around an SU(2) enhancement point of the string moduli space. The two deformation parameters epsilon_- and epsilon_+ of the Omega-supergravity background are then identified with the constant field-strength backgrounds for the anti-self-dual graviphoton and self-dual gauge field of the T-bar vector multiplet, respectively.Comment: 35 pages, typos corrected, published in NP

    On the perturbative corrections around D-string instantons

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    We study F4{\cal F}^4-threshold corrections in an eight dimensional S-dual pair of string theories, as a prototype of dual string vacua with sixteen supercharges. We show that the orbifold CFT description of D-string instantons gives rise to a perturbative expansion similar to the one appearing on the fundamental string side. By an explicit calculation, using the Nambu-Goto action in the static gauge, we show that the first subleading term agrees precisely on the two sides. We then give a general argument to show that the agreement extends to all orders.Comment: 12 page
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