Hasil untuk "hep-th"

T. Azeyanagi, R. Loganayagam, G. S. Ng et al.

A bstractWe construct a manifestly covariant differential Noether charge for theories with Chern-Simons terms in higher dimensional spacetimes. This is in contrast to Tachikawa’s extension of the standard Lee-Iyer-Wald formalism which results in a non-covariant differential Noether charge for Chern-Simons terms. On a bifurcation surface, our differential Noether charge integrates to the Wald-like entropy formula proposed by Tachikawa in [hep-th/0611141].

A. Vinayak, M. Sudha, R. Kumar et al.

Da-Wei Pang

We study thermodynamics of entanglement entropy for weakly excited states in certain non-conformal fields theories, whose gravity duals are given by non-conformal Dp-branes. We observe that the entanglement entropy of a sufficiently small system in non-conformal backgrounds still obeys a first-law like relation, just as the AdS counterparts investigated in arXiv: 1212.1164 [hep-th]. The effective temperature is proportional to the inverse of the size of the subsystem. The proportionality is a dimensionless constant which is only determined by the shape of the entangling region and independent of any coupling. This universality is confirmed by working with the ten-dimensional string frame metric as well as the lower-dimensional effective metric. When the entangling region is a strip and translational invariance is broken by metric fluctuations, we derive a first-law like relation where additional components of the stress energy tensor are involved.

S. Fedoruk, E. Ivanov, O. Lechtenfeld

We elaborate on a novel superconformal mechanics model possessing D(2, 1; α) symmetry and involving extra U(2) spin variables. It is the one-particle case of the $ \mathcal{N} = 4 $ superconformal matrix model recently proposed in arXiv:0812.4276 [hep-th], and it generalizes to arbitrary α≠0 the OSp(4|2) superconformal mechanics of arXiv:0905.4951 [hep-th]. As in the latter case, the U(2) spin variables are described by a Wess-Zumino action and define the first Hopf map S3 → S2 in the target space. Upon quantization, they represent a fuzzy sphere. We find the classical and quantum generators of the D(2, 1; α) superalgebra and their realization on the physical states. The super wavefunction encompasses various multiplets of the SU(2)R and SU(2)L subgroups of D(2, 1; α), with fixed isospins. The conformal potential is determined by the external magnetic field in the Wess-Zumino term, whose strength is quantized like in the OSp(4|2) case. As a byproduct, we reveal new invariant subspaces in the enveloping algebra of D(2, 1; α) for our quantum realization.

Jun Peng, Shuang Wu

Abstract We extend the method of Kerr/CFT correspondence recently proposed in arXiv:0809.4266 [hep-th] to the extremal (charged) Kerr black hole embedded in the five-dimensional Godel universe. With the aid of the central charges in the Virasoro algebra and the Frolov–Thorne temperatures, together with the use of the Cardy formula, we have obtained the microscopic entropies that precisely agree with the ones macroscopically calculated by Bekenstein–Hawking area law.

M. S. Bianchi, S. Penati, M. Siani

We consider marginal deformations of the superconformal ABJM/ABJ models which preserve $ \mathcal{N} = 2 $ supersymmetry. We determine perturbatively the spectrum of fixed points and study their infrared stability. We find a closed line of fixed points which is IR stable. The fixed point corresponding to the ABJM/ABJ models is stable under marginal deformations which respect the original SU(2)A × SU(2)B invariance, while deformations which break this group destabilize the theory which then flows to a less symmetric fixed point. We discuss the addition of flavor degrees of freedom. We prove that in general a flavor marginal superpotential does not destabilize the system in the IR. An exception is represented by a marginal coupling which mixes matter charged under different gauge sectors. Finally, we consider the case of relevant deformations which should drive the system to a strongly coupled IR fixed point recently investigated in arXiv:0909.2036 [hep-th].

P. Mnev

In this work we discuss the simplicial program for topological field theories for the case of non-abelian BF theory. Discrete BF theory with finite-dimensional space of fields is constructed for a triangulated manifold (or for a manifold equipped with cubical cell decomposition), that is in a sense equivalent to the topological BF theory on manifold. This discrete version allows one to calculate interesting quantities from the BF theory, like the effective action on cohomology, in terms of finite-dimensional integrals instead of functional integrals, as demonstrated in a series of explicit examples. We also discuss the interpretation of discrete BF action as the generating function for $qL_\infty$ structure (certain "one-loop version" of ordinary $L_\infty$ algebra) on the cell cochains of triangulation, related to the de Rham algebra of the underlying manifold by homotopy transfer procedure. This work is a refinement of older text hep-th/0610326.

R. Rashkov, M. Stanishkov

E. Martinec, W. Mcelgin

The supersymmetric (AdS3£S 3 )=ZN orbifold constructed by the authors in hep-th/0106171 is shown to describe AdS fragmentation, where flvebranes are emerging from the F1-NS5 background. The twisted sector moduli of the orbifold are the collective coordinates of groups of n5=N flvebranes. We discuss the relation between the descriptions of this background as a perturbative string orbifold and as a BPS state in the dual spacetime CFT. Finally, we attempt to apply the lessons learned to the description of BTZ black holes as AdS3 orbifolds and to related big crunch/big bang cosmological scenarios.

G. Arcioni, C. Dappiaggi

In a previous paper (Arcioni G and Dappiaggi C 2003 Preprint hep-th/0306142) we have started to explore the holographic principle in the case of asymptotically flat spacetimes and analysed, in particular, different aspects of the Bondi–Metzner–Sachs (BMS) group, namely the asymptotic symmetry group of any asymptotically flat spacetime. We continue this investigation in this paper. Having in mind an S-matrix approach with future and past null infinity playing the role of holographic screens on which the BMS group acts, we connect the IR sectors of the gravitational field with the representation theory of the BMS group. We analyse the (complicated) mapping between bulk and boundary symmetries pointing out differences with respect to the anti-de Sitter (AdS)/CFT set up. Finally, we construct a BMS phase space and a free Hamiltonian for fields transforming with respect to BMS representations. The last step is supposed to be an explorative investigation of the boundary data living on the degenerate null manifold at infinity.

C. Herzog, I. Klebanov

We derive type II supergravity solutions corresponding to space-filling regular and fractional Dp branes on (9 − p)-dimensional conical transverse spaces. Fractional Dp-branes are wrapped D(p + 2)-branes; therefore, our solutions exist only if the base of the cone has a non-vanishing Betti number b2. We also consider 11-dimensional SUGRA solutions corresponding to regular and fractional M2 branes on 8-dimensional cones whose base has a non-vanishing b3. (In this case a fractional M2-brane is an M5-brane wrapped over a 3-cycle.) We discuss the gauge theory intepretation of these solutions, as well as of the solutions constructed by Cvetiyc et al. in hep-th/0011023 and hep-th/0012011.

M. Arai, M. Naganuma, M. Nitta et al.

BPS wall solutions are obtained for N = 2 supersymmetric nonlinear sigma model with Eguchi- Hanson target manifold in a manifestly supersymmetric manner. The model is constructed by a massive hyper-Kahler quotient method both in the N = 1 superfield and in the N = 2 superfield (harmonic superspace). We describe the model in simple terms and give relations between various parameterizations which are useful to describe the model and the solution. Some more details can be found in our previous paper (1) (hep-th/0211103). This article is dedicated to Professor Hiroshi Ezawa on the occasion of his seventieth birthday.

Antonio Padilla

We derive the gravitational Hamiltonian starting from the Gauss–Bonnet action, keeping track of all surface terms. This is done using the language of orthonormal frames and forms to keep things as tidy as possible. The surface terms in the Hamiltonian give a remarkably simple expression for the total energy of a spacetime. This expression is consistent with energy expressions found in Preprint hep-th/0212292. However, we can apply our results whatever the choice of background and whatever the symmetries of the spacetime.

C. Burgess, F. Quevedo, Soo-Jong Rey et al.

We identify a time-dependent class of metrics with potential applications to cosmology, which emerge from negative-tension branes. The cosmology is based on a gen- eral class of solutions to Einstein-dilaton-Maxwell theory, presented in hep-th/0106120. We argue that solutions with hyperbolic or planar symmetry describe the gravitational interactions of a pair of negative-tension q-branes. These spacetimes are static near each brane, but become time-dependent and expanding at late epoch | in some cases asymptot- ically approaching ∞at space. We interpret this expansion as being the spacetime's response to the branes' presence. The time-dependent regions provide explicit examples of cosmo- logical spacetimes with past horizons and no past naked singularities. The past horizons can be interpreted as S-branes. We prove that the singularities in the static regions are repulsive to time-like geodesics, extract a cosmological \bounce" interpretation, compute the explicit charge and tension of the branes, analyse the classical stability of the solution (in particular of the horizons) and study particle production, deriving a general expression for Hawking's temperature as well as the associated entropy.

R. Gopakumar

We continue with the program of hep-th/0308184 to implement open-closed string duality on free gauge field theory (in the large N limit). In this paper we consider correlators such as h Q ni =1 TrΦ J i ( x i ) i . The Schwinger parametrisation of this n -point function exhibits a partial gluing up into a set of basic skeleton graphs. We argue that the moduli space of the planar skeleton graphs is exactly the same as the moduli space of genus zero Riemann surfaces with n holes. In other words, we can explicitly rewrite the n -point (planar) free field correlator as an integral over the moduli space of a sphere with n holes. A preliminary study of the integrand also indicates compatibility with a string theory on AdS . The details of our argument are quite insensitive to the specific form of the operators and generalise to diagrams of higher genus as well. We take this as evidence of the field theory’s ability to reorganise itself into a string theory.

A. Schwarz

It was shown by Connes, Douglas, Schwarz [hep-th/9711162] that one can compactify M(atrix) theory on a non-commutative torus To. We prove that compactifications on Morita equivalent tori are in some sense physically equivalent. This statement can be considered as a generalization of non-classical SL(2,Z)N duality conjectured by Connes, Douglas and Schwarz for compactifications on two-dimensional non-commutative tori.

K. Alkalaev, O. Shaynkman, M. Vasiliev

In this paper we discuss in detail the frame-like formulation of free bosonic massless higher-spin fields of general symmetry type in AdS(d), announced recently in hep-th/0311164, hep-th/0501108. Properties of gauge invariant and AdS covariant action functionals and their flat limits are carefully analyzed.

Matthias Ihl, T. Wrase

We apply the methods of DeWolfe et al. [hep-th/0505160] to a T^6/Z_4 orientifold model. This is the first step in an attempt to build a phenomenologically interesting meta-stable de Sitter model with small cosmological constant and standard model gauge groups.

Abstract Using gauge theory/string theory correspondence certain universal aspects of the strongly coupled four-dimensional gauge theory hydrodynamics were established in hep-th/0311175 . The analysis was performed in the framework of “membrane paradigm” approach to the fluctuations on the black brane stretched horizon. We confirm the universal result for the shear viscosity to the entropy density ratio for the strongly coupled N = 2 * gauge theory from explicit computation of the finite temperature Minkowski-space correlation functions in the dual supergravity geometry.

T. Quella

We construct the boundary WZNW functional for symmetry breaking D-branes on a group manifold which are localized along a product of a number of twisted conjugacy classes and which preserve an action of an arbitrary continuous subgroup. These branes provide a geometric interpretation for the algebraic formulation of constructing D-branes developed recently in hep-th/0203161. We apply our results to obtain new symmetry breaking and non-factorizing D-branes in the background SL(2, R) × SU(2).