Hasil untuk "hep-th"

Chien-Hao Liu, Shing-Tung Yau

We introduce a new action $S_{standard}^{(ρ,h; Φ,g,B,C)}$ for D-branes that is to D-branes as the Polyakov action is to fundamental strings. This `standard action' is abstractly a non-Abelian gauged sigma model --- based on maps $\varphi: (X^{\!A\!z},E;\nabla)\rightarrow Y$ from an Azumaya/matrix manifold $X^{\!A\!z}$ with a fundamental module $E$ with a connection $\nabla$ to $Y$ --- enhanced by the dilaton term, the gauge-theory term, and the Chern-Simons/Wess-Zumino term that couples $(\varphi,\nabla)$ to Ramond-Ramond field. In a special situation, this new theory merges the theory of harmonic maps and a gauge theory, with a nilpotent type fuzzy extension. With the analysis developed in D(13.1) (arXiv:1606.08529 [hep-th]) for such maps and an improved understanding of the hierarchy of various admissible conditions on the pairs $(\varphi,\nabla)$ beyond D(13.2.1) (arXiv:1611.09439 [hep-th]) and how they resolve the built-in obstruction to pull-push of covariant tensors under a map from a noncommutative manifold to a commutative manifold, we develop further in this note some covariant differential calculus needed and apply them to work out the first variation --- and hence the corresponding equations of motion for D-branes --- of the standard action and the second variation of the kinetic term for maps and the dilaton term in this action. Compared with the non-Abelian Dirac-Born-Infeld action constructed in D(13.1) along the same line, the current note brings the Nambu-Goto-string-to-Polyakov-string analogue to D-branes. The current bosonic setting is the first step toward the dynamics of fermionic D-branes (cf. D(11.2): arXiv:1412.0771 [hep-th]) and their quantization as fundamental dynamical objects, in parallel to what happened to the theory of fundamental strings during years 1976--1981.

Malak Khouchen, Josef Klusoň

We study D1-brane in AdS_3 times S^3 kappa-deformed background with non-trivial dilaton and Ramond-Ramond fields. We consider purely time-dependent and spatially-dependent ansatz where we study the solutions of the equations of motion for D1-brane in given background. We find that the behavior of these solutions crucially depends on the value of the parameter a that was introduced in [arXiv:1411.1066 [hep-th]].

Mitsutoshi Fujita, Yasuyuki Hatsuda, Tadashi Takayanagi

In this paper, we study the Lorentzian AdS wormhole solutions constructed in arXiv:0808.2481 [hep-th]. Each of them is a classical solution interpolating between an AdS space and a flat space in type IIB supergravity. We calculate the holographic entanglement entropy to probe this geometry. Our analysis shows that there exits a mass gap in its holographic dual gauge theory and that the entanglement between the two boundaries is rather suppressed than that we naively expect for wormholes. We also examine the holographic conductivity on a probe D-brane in this spacetime.

Marco Bochicchio

We have computed in [arXiv:1107.4320 (hep-th)] the glueballs spectrum in a certain sector of the large-N YM theory by solving by a change of variables the holomorphic loop equation for cusped twistor Wilson loops supported on certain Lagrangian submanifolds and by evaluating the correlators of surface operators supported on these Lagrangian submanifolds. We have shown that the correlators of composite surface operators of length L reproduce in the large-L limit the leading logarithms of perturbation theory of the corresponding glueballs propagators, including the correct anomalous dimensions. In this paper we show that the correlators of surface operators match in the large-L limit the stronger constraints arising by the operator product expansion, according to Migdal technique of computing the spectral sum over the glueballs including the subleading asymptotics given by the Euler formula. Finally, we discuss correlators of surface operators for finite L.

N. Berkovits, J. Hoogeveen, Kostas Skenderis

This is the first of a series of two papers where decoupling of unphysical states in the minimal pure spinor formalism is investigated. The multi-loop amplitude prescription for the minimal pure spinor superstring formulated in hep-th/0406055 involves the insertion of picture changing operators in the path integral. These operators are BRST closed in a distributional sense and depend on a number of constant tensors. One can trace the origin of these insertions to gauge fixing, so the amplitudes are formally independent of the constant tensors. We show however by explicit tree-level and one-loop computations that the picture changing operators are not BRST closed inside correlators and the amplitudes do depend on these constant tensors. This is due to the fact that the gauge fixing condition implicit in the existing minimal amplitude prescription is singular and this can lead to Lorentz violation and non-decoupling of BRST exact states. As discussed in hep-th/0406055, a manifestly Lorentz invariant prescription can be obtained by integrating over the constant tensors and in the sequel to this paper, it is shown that when one includes these integrations unphysical states do decouple to all orders despite the fact that the PCO's are not BRST closed inside correlators.

Jun-Jin Peng, Shuang-Qing Wu

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 Gödel 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.

G. Sardanashvily

Jet formalism provides the adequate mathematical formulation of classical field theory, reviewed in hep-th/0612182v1. A formulation of QFT compatible with this classical one is discussed. We are based on the fact that an algebra of Euclidean quantum fields is graded commutative, and there are homomorphisms of the graded commutative algebra of classical fields to this algebra. As a result, any variational symmetry of a classical Lagrangian yields the identities which Euclidean Green functions of quantum fields satisfy.

Harold Steinacker, George Zoupanos

We include fermions to the model proposed in hep-th/0606021, and obtain a renormalizable 4-dimensional SU(N) gauge theory which spontaneously generates fuzzy extra dimensions and behaves like Yang-Mills theory on M^4 \times S^2. We find a truncated tower of fermionic Kaluza-Klein states transforming under the low-energy gauge group, which is found to be either SU(n), or SU(n_1) x SU(n_2) x U(1). The latter case implies a nontrivial U(1) flux on S^2, leading to would-be zero modes for the bifundamental fermions. In the non-chiral case they may pair up to acquire a mass, and the emerging picture is that of mirror fermions. We discuss the possible implementation of a chirality constraint in 6 dimensions, which is nontrivial at the quantum level due to the fuzzy nature of the extra dimensions.

I. Khriplovich, R. Sen'kov

We demonstrate that criticisms concerning our work nucl-th/9704043, made in the recent preprint hep-ph/9903352, are unfounded. The improvements over our results claimed in hep-ph/9903352 are in fact spurious, being based mainly on misunderstandings and on dubious theoretical models.

Oleg Zaboronsky

A class of quantum field theories invariant with respect to the action of an odd vector field Q on a source supermanifold Σ is considered. We suppose that Q satisfies the conditions of one of the localization theorems (Szabo R 1996 Equivariant localization of path integrals Preprint hep-th/9608068). The Q-invariant sector of a field theory from the above class is then shown to be equivalent to the quantum field theory defined on the zero locus of the vector field Q.

T. Prestidge

In a quantum theory of gravity, fluctuations about the vacuum may be considered as Planck scale virtual black holes appearing and annihilating in pairs. Incident fields scattering from such fluctuations would lose quantum coherence. In a recent paper (hep-th/9705147), Hawking and Ross obtained an estimate for the magnitude of this loss in the case of a scalar field. Their calculation exploited the separability of the conformally invariant scalar wave equation in the electrovac C metric background, which is justified as a sufficiently good description of a virtual black hole pair in the limit considered. In anticipation of extending this result, the Teukolsky equations for incident fields of higher spin are separated on the vacuum C metric background and solved in the same limit. With the exception of spin 2 fields, these equations are shown in addition to be valid on the electrovac C metric background. The angular solutions are found to reduce to the spin- weighted spherical harmonics, and the radial solutions are found to approach hypergeometrics close to the horizons. By defining appropriate scattering boundary conditions, these solutions are then used to estimate the transmission and reflection coefficients for an incident field of spin s. The transmission coefficient is required in order to estimate the loss of quantum coherence of an incident field through scattering off virtual black holes.

Y. Isozumi, M. Nitta, K. Ohashi et al.

We review recent results on solitons in supersymmetric (SUSY) non-Abelian gauge theories, focusing on our papers: hep-th/0405194, hep-th/0405129, and hep-th/0404198. We construct the BPS multi-wall solutions in supersymmetric U(N_C) gauge theories in five dimensions with N_F(>N_C) hypermultiplets in the fundamental representation. Exact solutions are obtained with full generic moduli for infinite gauge coupling. Total moduli space of the BPS non-Abelian walls is found to be the complex Grassmann manifold SU(N_F) / [SU(N_C)\times SU(N_F-N_C) \times U(1)]. A 1/4 BPS equation is also studied which gives combinations of vortices, walls and monopoles. The full moduli space of the 1/4 BPS equation is found to be the space of all holomorphic maps from a complex plane to the wall moduli space. Exact solutions of the 1/4 BPS equation are also obtained for infinite gauge coupling.

Nakwoo Kim

We continue the study of supersymmetric type IIB pp-wave solutions by Maldacena and Maoz (hep-th/0207284), who showed Ramond-Ramond five-forms can induce potential terms in the light cone string actions which are nonlinear sigma models with special holonomy target spaces. We show that nonvanishing Ramond-Ramond three-forms provide extra potential terms involving Killing vectors in the string action and identify the supersymmetry requirements. In particular, in solutions with (1,1) worldsheet supersymmetry, the Killing vectors are required to be self-dual in Spin(7).

L. Bonora, C. Maccaferri, P. Prester

We analyze the fluctuations of the dressed sliver solution found in a previous paper, hep-th/0311198, in the operator formulation of Vacuum String Field Theory. We derive the tachyon wave function and then analyze the higher level fluctuations. We show that the dressing is responsible for implementing the transversality condition on the massless vector. In order to consistently deal with the singular k=0 mode we introduce a string midpoint regulator and we show that it is possible to accommodate all the open string states among the solutions to the linearized equations of motion. We finally show how the dressing can give rise to the correct ratio between the energy density of the dressed sliver and the brane tension computed via the three-tachyons-coupling.

S. Sin

Abstract We study the localized tachyon condensation in their mirror Landau–Ginzburg picture. We completely determine the decay mode of an unstable orbifold C r / Z n , r =1,2,3 under the condensation of a tachyon with definite R-charge and mass by extending the Vafa's work hep-th/0111105 . Here, we give a simple method that works uniformly for all C r / Z n . For C 2 / Z n , where method of toric geometry works, we give a proof of equivalence of our method with toric one. For C r / Z n cases, the orbifolds decay into sum of r far separated orbifolds.

M. Bianchi

Kazumi Okuyama

We study the annulus amplitudes in the (2,4) minimal superstring theory using the continuum worldsheet approach. Our results reproduce the semiclassical behavior of the wavefunctions of FZZT-branes recently studied in hep-th/0412315 using the dual matrix model. We also study the multi-point functions of neutral FZZT-branes and find the agreement between their semiclassical limit and the worldsheet annulus calculation.

M. Bordag, M. Hellmund, K. Kirsten

The vacuum energy of a scalar field in a spherically symmetric background field is considered. Based on previous work [hep-th/9608070], the numerical procedure is refined further and applied to several examples. We provide numerical evidence that repulsive potentials lead to positive contributions to the vacuum energy. Furthermore, the crucial role played by bound-states is clearly seen.

Supergravity, C. Burgess, F. Quevedo et al.

A C R Mendes, C. Neves, W. Oliveira