Hasil untuk "hep-th"

P. Moshin, A. Reshetnyak

We introduce the notion of finite BRST–anti-BRST transformations for constrained dynamical systems in the generalized Hamiltonian formalism, both global and field-dependent, with a doublet λa, a = 1, 2, of anticommuting Grassmann parameters and find explicit Jacobians corresponding to these changes of variables in the path integral. It turns out that the finite transformations are quadratic in their parameters. Exactly as in the case of finite field-dependent BRST–anti-BRST transformations for the Yang–Mills vacuum functional in the Lagrangian formalism examined in our previous paper [arXiv:1405.0790 [hep-th]], special field-dependent BRST–anti-BRST transformations with functionally-dependent parameters λa = ∫ dt(saΛ), generated by a finite even-valued function Λ(t) and by the anticommuting generators sa of BRST–anti-BRST transformations, amount to a precise change of the gauge-fixing function for arbitrary constrained dynamical systems. This proves the independence of the vacuum functional under such transformations. We derive a new form of the Ward identities, depending on the parameters λa and study the problem of gauge dependence. We present the form of transformation parameters which generates a change of the gauge in the Hamiltonian path integral, evaluate it explicitly for connecting two arbitrary Rξ-like gauges in the Yang–Mills theory and establish, after integration over momenta, a coincidence with the Lagrangian path integral [arXiv:1405.0790 [hep-th]], which justifies the unitarity of the S-matrix in the Lagrangian approach.

J. Klusoň

We perform the Hamiltonian analysis of the bimetric theory of gravity introduced in S. F. Hassan and R. A. Rosen, J. High Energy Phys.1202, 126 (2012), arXiv:1109.3515 [hep-th]. We carefully analyze the requirement of the preservation of all constraints and we find that there is no additional constraint that could eliminate the ghost mode.

D. Klemm

Using the general recipe given in arXiv:0804.0009, where all timelike super-symmetric solutions of $ \mathcal{N} = 2 $, D = 4 gauged supergravity coupled to abelian vector multiplets were classified, we construct genuine rotating supersymmetric black holes in AdS4 with nonconstant scalar fields. This is done for the SU(1, 1)/U(1) model with prepotential F = −iX0X1. In the static case, the black holes are uplifted to eleven dimensions, and generalize the solution found in hep-th/0105250 corresponding to membranes wrapping holomorphic curves in a Calabi-Yau five-fold. The constructed rotating black holes preserve one quarter of the supersymmetry, whereas their near-horizon geometry is one half BPS. Moreover, for constant scalars, we generalize (a supersymmetric subclass of) the Plebanski-Demianski solution of cosmological Einstein-Maxwell theory to an arbitrary number of vector multiplets. Remarkably, the latter turns out to be related to the dimensionally reduced gravitational Chern-Simons action.

Paul D. Johnson

In math.AG/0207233, Okounkov and Pandharipande gave an operator formalism for computing the equivariant Gromov-Witten theory of the projective line. This thesis extends their result to orbifold lines. In the effective case the theory is again governed by the 2-Toda hierarchy. In the ineffective case the decomposition conjecture of hep-th/0606034 is verified.

H. Verlinde, E. Verlinde

Previous studies of high-energy scattering in QCD have shown a remarkable correspondence with two-dimensional field theory. In this paper we formulate a simple effective model in which this two-dimensional nature of the interactions is manifest. Starting from the (3+1)-dimensional Yang-Mills action, we implement the high energy limit $s\! >\! > \! t$ via a scaling argument and we derive from this a simplified effective theory. This effective theory is still (3+1)-dimensional, but we show that its interactions can to leading order be summarized in terms of a two-dimensional sigma-model defined on the transverse plane. Finally, we verify that our formulation is consistent with known perturbative results. This is a revised and extended version of hep-th 9302104. In particular, we have added a section that clarifies the connection with Lipatov's gluon emission vertex.

Peter Lee, H. Ooguri, Jongwon Park

We construct boundary states for the AdS_2 D-branes in AdS_3. We show that, in the semi-classical limit, the boundary states correctly reproduce geometric configurations of these branes. We use the boundary states to compute the one loop free energy of open string stretched between the branes. The result agrees precisely with the open string computation in hep-th/0106129.

R. Kallosh, L. Kofman, Andrei Linde et al.

The possibility to study the M/string theory cosmology via 5d bulk & brane action is investigated. The role of the 4-form field in the theory of BPS branes in 5d is clarified. We describe arguments suggesting that the effective 4d description of the universe in the ekpyrotic scenario (hep-th/0103239) should lead to contraction rather than expansion of the universe. To verify these arguments, we study the full 5d action prior to its integration over the 5th dimension. We show that if one adds the potential V(Y) to the action of the bulk brane, then the metric ansatz used in the ekpyrotic scenario does not solve the dilaton and gravitational equations. To find a consistent cosmological solution one must use a more general metric ansatz and a complete 5d description of the brane interaction instead of simply adding an effective 4d bulk brane potential V(Y).

I. Buchbinder, A. Petrov, A. Tseytlin

Abstract We compute the leading low-energy term in the planar part of the 2-loop contribution to the effective action of N =4 SYM theory in 4 dimensions, assuming that the gauge group SU ( N +1) is broken to SU ( N )× U (1) by a constant scalar background X . While the leading 1-loop correction is the familiar c 1 F 4 /| X | 4 term, the 2-loop expression starts with c 2 F 6 /| X | 8 . The 1-loop constant  c 1 is known to be equal to the coefficient of the F 4 term in the Born–Infeld action for a probe D3-brane separated by distance | X | from a large number N of coincident D3-branes. We show that the same is true also for the 2-loop constant c 2 : it matches the coefficient of the F 6 term in the D3-brane probe action. In the context of the AdS/CFT correspondence, this agreement suggests a non-renormalization of the coefficient of the F 6 term beyond two loops. Thus the result of hep-th/9706072 about the agreement between the v 6 term in the D0-brane supergravity interaction potential and the corresponding 2-loop term in the (1+0)-dimensional reduction of N =4 SYM theory has indeed a direct generalization to 1+3 dimensions, as conjectured earlier in hep-th/9709087. We also discuss the issue of gauge theory—supergravity correspondence for higher order ( F 8 , etc.) terms.

E.K.Sklyanin

LPTHE-93-42hep-th/9308060Abstract. For the integrable N-particle Calogero-Moser system with ellipticpotential it is shown that the Lax operator found by Krichever possesses a classicalr-matrix structure. The r-matrix is a natural generalisation of the matrix foundrecently by Avan and Talon (hep-th/9210128) for the trigonometric potential. Ther-matrix depends on the spectral parameter and only half of the dynamical variables(particles’ coordinates). It satisfies a generalized Yang-Baxter equation involvinganother dynamical matrix.

A. Antonov, B. Feigin

Abstract In this article we propose an algebraic universal procedure for deriving the “fusion rules” and the Baxter equation for any integrable model with U q ( sl 2 ) symmetry by means of the quantum inverse scattering method. The universal Baxter Q-operator is obtained from a certain infinite dimensional representation called q-oscillator representation of the universal R-matrix for the U q ( sl 2 ) affine algebra (first proposed by V. Bazhanov, S. Lukyanov and A. Zamolodchikov [hep-th/9604044] for the quantum KdV case). We also examine the algebraic properties of the Q-operator.

Juan Maldacenaa, H. Ooguri

Miao Li

We discuss a class of matrix models describing cosmology with a light-like singularity, generalizing the model proposed by Craps et al. in [hep-th/0506180].

James T. Liu, D. Vaman, W. Wen

Abstract We extend the construction of bubbling 1/2 BPS solutions of Lin, Lunin and Maldacena (H. Lin, O. Lunin, J. Maldacena, JHEP 0410 (2004) 025, hep-th/0409174 ) in two directions. First we enquire whether bubbling 1/2 BPS solutions can be constructed in minimal 6d supergravity and second we construct solutions that are 1/4 BPS in type IIB. We find that the S 1 × S 1 bosonic reduction of ( 1 , 0 ) 6d supergravity to 4d gravity coupled to 2 scalars and a gauge field is consistent only provided that the gauge field obeys a constraint ( F ∧ F = 0 ). This is to be contrasted to the case of the S 3 × S 3 bosonic reduction of type IIB supergravity to 4d gravity, 2 scalars and a gauge field, where consistency is achieved without imposing any such constraints. Therefore, in the case of ( 1 , 0 ) 6d supergravity we are able to construct 1/2 BPS solutions, similar to those derived in type IIB, provided that this additional constraint is satisfied. This ultimately prohibits the construction of a family of 1/2 BPS solutions corresponding to a bubbling AdS 3 × S 3 geometry. Returning to type IIB solutions, by turning on an axion–dilaton field we construct a family of bubbling 1/4 BPS solutions. This corresponds to the inclusion of back-reacted D7 branes to the solutions of Lin, Lunin and Maldacena.

Kazumi Okuyama

We study the star algebra of ghost sector in vacuum string field theory (VSFT). We show that the star product of two states in the Siegel gauge is BRST exact if we take the BRST charge to be the one found in hep-th/0108150, and the BRST exact states are nil factors in the star algebra. By introducing a new star product defined on the states in the Siegel gauge, the equation of motion of VSFT is characterized as the projection condition with respect to this new product. We also comment on the comma form of string vertex in the ghost sector.

G. Geshnizjani, D. Chung, N. Afshordi

Recently, new arguments [E. Barausse, S. Matarrese, and A. Riotto, Phys. Rev. D 71, 063537 (2005).][E. W. Kolb, S. Matarrese, A. Notari, and A. Riotto, hep-th/0503117 [Phys. Rev. Lett. (to be published)].] for how corrections from super-Hubble modes can explain the present-day acceleration of the universe have appeared in the literature. However, in this paper, we argue that, to second order in spatial gradients, these corrections only amount to a renormalization of local spatial curvature, and thus cannot account for the negative deceleration. Moreover, cosmological observations already put severe bounds on such corrections, at the level of a few percent, while in the context of inflationary models, these corrections are typically limited to {approx}10{sup -5}. Currently there is no general constraint on the possible correction from higher order gradient terms, but we argue that such corrections are even more constrained in the context of inflationary models.

Ulf Gran, J. Gutowski, G. Papadopoulos et al.

We reduce the classification of all supersymmetric backgrounds of IIB supergravity to the evaluation of the Killing spinor equations and their integrability conditions, which contain the field equations, on five types of spinors. This extends the work of Gran et al (2005 Class. Quantum Grav. 22 118 (Preprint hep-th/0503046)) to IIB supergravity. We give the expressions of the Killing spinor equations on all five types of spinors. In this way, the Killing spinor equations become a linear system for the fluxes, geometry and spacetime derivatives of the functions that determine the Killing spinors. This system can be solved to express the fluxes in terms of the geometry and determine the conditions on the geometry of any supersymmetric background. Similarly, the integrability conditions of the Killing spinor equations are turned into a linear system. This can be used to determine the field equations that are implied by the Killing spinor equations for any supersymmetric background. We show that these linear systems simplify for generic backgrounds with maximal and half-maximal number of H-invariant Killing spinors, H ⊂ Spin(9, 1). In the maximal case, the Killing spinor equations factorize, whereas in the half-maximal case they do not. As an example, we solve the Killing spinor equations of backgrounds with two -invariant Killing spinors. We also solve the linear systems associated with the integrability conditions of maximally supersymmetric —and —backgrounds and determine the field equations that are not implied by the Killing spinor equations.

F. Delduc, E. Ivanov

Exploiting the gauging procedure developed by us in hep-th/0605211, we study the relationships between the models of N=4 mechanics based on the off-shell multiplets (4,4,0) and (1,4,3). We make use of the off-shell N=4, d=1 harmonic superspace approach as most adequate for treating this circle of problems. We show that the most general sigma-model type superfield action of the multiplet (1,4,3) can be obtained in a few non-equivalent ways from the (4,4,0) actions invariant under certain three-parameter symmetries, through gauging the latter by the appropriate non-propagating gauge multiplets. We discuss in detail the gauging of both the Pauli–Gursey SU(2) symmetry and the Abelian three-generator shift symmetry. We reveal the (4,4,0) origin of the known mechanisms of generating potential terms for the multiplet (1,4,3), as well as of its superconformal properties. A new description of this multiplet in terms of unconstrained harmonic analytic gauge superfield is proposed. It suggests, in particular, a novel mechanism of generating the (1,4,3) potential terms via coupling to the fermionic off-shell N=4 multiplet (0,4,4).

J. Minahan, A. Tirziu, A. Tseytlin

In a previous paper [hep-th/0509071], it was shown that quantum 1/J corrections to the BMN spectrum in an effective Landau-Lifshitz (LL) model match with the results from the one-loop gauge theory, provided one chooses an appropriate regularization. In this paper we continue this study for the conjectured Bethe ansatz for the long range spin chain representing perturbative large-N = 4 Super Yang-Mills in the SU(2) sector, and the ``quantum string" Bethe ansatz for its string dual. The comparison is carried out for corrections to BMN energies up to order 3 in the effective expansion parameter = λ/J2. After determining the ``gauge-theory'' LL action to order 3, which is accomplished indirectly by fixing the coefficients in the LL action so that the energies of circular strings match with the energies found using the Bethe ansatz, we find perfect agreement. We interpret this as further support for an underlying integrability of the system. We then consider the ``string-theory'' LL action which is a limit of the classical string action representing fast string motion on an S3 subspace of S5 and compare the resulting 3/J2 corrections to the prediction of the ``string'' Bethe ansatz. As in the gauge case, we find precise matching. This indicates that the LL hamiltonian supplemented with a normal ordering prescription and ζ-function regularization reproduces the full superstring result for the 1/J2 corrections, and also signifies that the string Bethe ansatz does describe the quantum BMN string spectrum to order 1/J2. We also comment on using the quantum LL approach to determine the non-analytic contributions in λ that are behind the strong to weak coupling interpolation between the string and gauge results.

G. Semenoff, D. Young

Abstract Correlation functions of 1 / 4 BPS Wilson loops with the infinite family of 1 / 2 BPS chiral primary operators are computed in N = 4 super-Yang–Mills theory by summing planar ladder diagrams. Leading loop corrections to the sum are shown to vanish. The correlation functions are also computed in the strong-coupling limit by examining the supergravity dual of the loop–loop correlator. The strong coupling result is found to agree with the extrapolation of the planar ladders. The result is related to known correlators of 1 / 2 BPS Wilson loops and 1 / 2 BPS chiral primaries by a simple re-scaling of the coupling constant, similar to an observation of Drukker [N. Drukker, hep-th/0605151] for the case of the 1 / 4 BPS loop vacuum expectation value.

Vladimir Kazakov, A. Tseytlin

Trying to interpret recent matrix model results (hep-th/0101011) we discuss computation of classical free energy of exact dilatonic 2-d black hole from the effective action of string theory. The euclidean space-time action evaluated on the black hole background is divergent due to linear dilaton vacuum contribution, and its finite part depends on a subtraction procedure. The thermodynamic approach based on subtracting the vacuum contribution for fixed values of temperature and dilaton charge at the ``wall" gives (as in the leading-order black hole case) S = M/T for the entropy and zero value for the free energy F. We suggest that in order to establish a correspondence with a non-vanishing matrix model result for F one may need an alternative reparametrization-invariant subtraction procedure using analogy with non-critical string theory (i.e. replacing the spatial coordinate by the dilaton field). The subtraction of the dilaton divergence then produces a finite value for the free energy. We also propose a microscopic estimate for the entropy and energy of the black hole based on the contribution of non-singlet states of the matrix model.