Hasil untuk "hep-th"

Yuji Sugawara

One of interesting issues in two-dimensional superconformal field theories is the existence of anomalous modular transformation properties appearing in some non-compact superconformal models, corresponding to the `mock modularity' in mathematical literature. I review a series of my studies on this issue in collaboration with T. Eguchi, mainly focusing on the papers [arXiv:1012.5721 [hep-th]], [arXiv:1407.7721 [hep-th]], [arXiv:1603.02903 [hep-th]].

Da-Wei Pang

We study holographic entanglement entropy of non-local field theories both at extremality and finite temperature. The gravity duals, constructed in arXiv:1208.3469 [hep-th], are characterized by a parameter $w$. Both the zero temperature backgrounds and the finite temperature counterparts are exact solutions of Einstein-Maxwell-dilaton theory. For the extremal case we consider the examples with the entangling regions being a strip and a sphere. We find that the leading order behavior of the entanglement entropy always exhibits a volume law when the size of the entangling region is sufficiently small. We also clarify the condition under which the next-to-leading order result is universal. For the finite temperature case we obtain the analytic expressions both in the high temperature limit and in the low temperature limit. In the former case the leading order result approaches the thermal entropy, while the finite contribution to the entanglement entropy at extremality can be extracted by taking the zero temperature limit in the latter case. Moreover, we observe some peculiar properties of the holographic entanglement entropy when $w=1$.

J. Klusoň

A bstractWe perform the Hamiltonian analysis of some form of the non-linear massive gravity action that is formulated in the Stückelberg formalism. Following seminal analysis performed in arXiv:1203.5283 [hep-th] we find that this theory possesses one primary constraint which could eliminate one additional mode in this theory. We performed the explicit Hamiltonian analysis of two dimensional non-linear massive gravity and we found that this is theory free from the ghosts.

D. Marsh

A model is presented in the philosophy of the "String Axiverse" of Arvanitaki et al (arXiv:0905.4720v2 [hep-th]) that incorporates a coupling of ultralight axions to their corresponding moduli through the mass term. The light fields roll in their potentials at late times and contribute to the dark sector energy densities in the cosmological expansion. The addition of a coupling and extra field greatly enrich the possible phenomenology of the axiverse. There are a number of interesting phases where the axion and modulus components behave as Dark Matter or Dark Energy and can have considerable and distinct effects on the expansion history of the universe by modifying the equation of state in the past or causing possible future collapse of the universe. In future such a coupling may help to alleviate fine tuning problems for cosmological axions. We motivate and present the model, and briefly explore its cosmological consequences numerically.

G. Mandal, T. Morita

We consider two-dimensional large N gauge theory with D adjoint scalars on a torus, which is obtained from a D+2-dimensional pure Yang-Mills theory on T{sup D+2} with D small radii. The two-dimensional model has various phases characterized by the holonomy of the gauge field around noncontractible cycles of the 2-torus. We determine the phase boundaries and derive the order of the phase transitions using a method developed in an earlier work (hep-th/0910.4526), which is nonperturbative in the 't Hooft coupling and uses a 1/D expansion. We embed our phase diagram in the more extensive phase structure of the D+2-dimensional Yang-Mills theory and match with the picture of a cascade of phase transitions found earlier in lattice calculations. We also propose a dual gravity system based on a Scherk-Schwarz compactification of a D2 brane wrapped on a 3-torus and find a phase structure which is similar to the phase diagram found in the gauge theory calculation.

B. Hoare, A. Tseytlin

Motivated by its relation to the Pohlmeyer reduction of AdS5 × S5 superstring theory we continue the investigation of the generalized sine-Gordon model defined by SO(N + 1)/SO(N) gauged WZW theory with an integrable potential. Extending our previous work (arXiv:0912.2958) we compute the one-loop two-particle S-matrix for the elementary massive excitations. In the N = 2 case corresponding to the complex sine-Gordon theory it agrees with the charge-one sector of the quantum soliton S-matrix proposed in hep-th/9410140. In the case of N > 2 when the gauge group SO(N) is non-abelian we find a curious anomaly in the Yang-Baxter equation which we interpret as a gauge artifact related to the fact that the scattered particles are not singlets under the residual global subgroup of the gauge group.

R. Manvelyan, K. Mkrtchyan, W. Ruehl

Several trilinear interactions of higher spin fields involving two equal (s=s1=s2) and one higher even (s3⩾2s) spin are presented. Interactions are constructed on the Lagrangian level using Noether's procedure together with the corresponding next to free level fields of the gauge transformations. In certain cases when the number of derivatives in the transformation is 2s−1 the interactions lead to the currents constructed from the generalization of the gravitational Bell–Robinson tensors. In other cases when the number of derivatives in the transformation is more than 2s−1 we obtain the finite tower of interactions with smaller even spins less than s3 in full agreement with our previous results for the interaction of the higher even spins field with a conformal scalar [R. Manvelyan, K. Mkrtchyan, Conformal invariant interaction of a scalar field with the higher spin field in AdSD, arXiv:0903.0058 [hep-th]; R. Manvelyan, W. Ruhl, Conformal coupling of higher spin gauge fields to a scalar field in AdS4 and generalized Weyl invariance, Phys. Lett. B 593 (2004) 253 arXiv:hep-th/0403241].

I. Amado, Carlos Hoyos-Badajoz, K. Landsteiner et al.

We continue our investigations on the relation between hydrodynamic and higher quasinormal modes in the AdS black hole background started in arXiv:0710.4458 [hep-th]. As is well known, the quasinormal modes can be interpreted as the poles of the retarded Green functions of the dual  = 4 gauge theory at finite temperature. The response to a generic perturbation is determined by the residues of the poles. We compute these residues numerically for energy-momentum and R-charge correlators. We find that the diffusion modes behave in a similar way: at small wavelengths the residues go over into a form of a damped oscillation and therefore these modes decouple at short distances. The sound mode behaves differently: its residue does not decay and at short wavelengths this mode behaves as the higher quasinormal modes. Applications of our findings include the definition of hydrodynamic length and time scales. We also show that the quasinormal modes, including the hydrodynamic diffusion modes, obey causality.

A. Schellekens

E. Ivanov, O. Lechtenfeld, A. Sutulin

Using the N=4 superspace approach in one dimension (time), we construct general N=8 supersymmetric mechanics actions for the multiplets (b,8,8−b) classified in hep-th/0406015, with the main focus on the previously unexplored cases of (8,8,0), (7,8,1) and (6,8,2), as well as on (5,8,3) for completeness. N=8 supersymmetry of the action amounts to a harmonicity condition for the Lagrangian with respect to its superfield arguments. We derive the generic off-shell component action for the “root” multiplet (8,8,0), prove that the actions for all other multiplets follow from it through automorphic dualities and argue that this hierarchical structure is universal. The bosonic target geometry in all cases is conformally flat, with a unique scalar potential (except for the root multiplet). We show that the N=4 superfield constraints respect the full R-symmetry and find the explicit realization of its quotient over the manifest R-symmetry on superfields and component fields. Several R-symmetric N=4 superfield Lagrangians with N=8 supersymmetry are either newly found or reproduced by a simple universal method.

A. Galajinsky, O. Lechtenfeld, K. Polovnikov

We continue the research initiated in hep-th/0607215 and apply our method of conformal automorphisms to generate various = 4 superconformal quantum many-body systems on the real line from a set of decoupled particles extended by fermionic degrees of freedom. The {su}(1,1|2) invariant models are governed by two scalar potentials obeying a system of nonlinear partial differential equations which generalizes the Witten-Dijkgraaf-Verlinde-Verlinde equations. As an application, the = 4 superconformal extension of the three-particle (A-type) Calogero model generates a unique G2-type Hamiltonian featuring three-body interactions. We fully analyze the = 4 superconformal three- and four-particle models based on the root systems of A1⊕G2 and F4, respectively. Beyond Wyllard's solutions we find a list of new models, whose translational non-invariance of the center-of-mass motion fails to decouple and extends even to the relative particle motion.

H. Steinacker, G. 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 M4 × S2. 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(n1) × SU(n2) × U(1). The latter case implies a nontrivial U(1) flux on S2, 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.

A. Misra, P. Shukla

Abstract We consider two sets of issues in this paper. The first has to do with moduli stabilization, existence of “area codes” [A. Giryavets, New attractors and area codes, JHEP 0603 (2006) 020, hep-th/0511215 ] and the possibility of getting a non-supersymmetric dS minimum without the addition of D 3 ¯ -branes as in KKLT for type II flux compactifications. The second has to do with the “inverse problem” [K. Saraikin, C. Vafa, Non-supersymmetric black holes and topological strings, hep-th/0703214 ] and “fake superpotentials” [A. Ceresole, G. Dall'Agata, Flow equations for non-BPS extremal black holes, JHEP 0703 (2007) 110, hep-th/0702088 ] for extremal (non-)supersymmetric black holes in type II compactifications. We use (orientifold of) a “Swiss cheese” Calabi–Yau [J.P. Conlon, F. Quevedo, K. Suruliz, Large-volume flux compactifications: Moduli spectrum and D3/D7 soft supersymmetry breaking, JHEP 0508 (2005) 007, hep-th/0505076 ] expressed as a degree-18 hypersurface in WCP 4 [ 1 , 1 , 1 , 6 , 9 ] in the “large-volume-scenario” limit [V. Balasubramanian, P. Berglund, J.P. Conlon, F. Quevedo, Systematics of moduli stabilisation in Calabi–Yau flux compactifications, JHEP 0503 (2005) 007, hep-th/0502058 ]. The main result of our paper is that we show that by including non-perturbative α ′ and instanton corrections in the Kahler potential and superpotential [T.W. Grimm, Non-perturbative corrections and modularity in N = 1 type IIB compactifications, arXiv: 0705.3253 [hep-th] ], it may be possible to obtain a large-volume non-supersymmetric dS minimum without the addition of anti-D3 branes a la KKLT. The chosen Calabi–Yau has been of relevance also from the point of other studies of Kahler moduli stabilization via non-perturbative instanton contributions [F. Denef, M.R. Douglas, B. Florea, Building a better racetrack, JHEP 0406 (2004) 034, hep-th/0404257 ] and non-supersymmetric AdS vacua (and their subsequent dS-uplifts) using ( α ′ ) 3 corrections to the Kahler potential [V. Balasubramanian, P. Berglund, J.P. Conlon, F. Quevedo, Systematics of moduli stabilisation in Calabi–Yau flux compactifications, JHEP 0503 (2005) 007, hep-th/0502058 ; K. Becker, M. Becker, M. Haack, J. Louis, Supersymmetry breaking and alpha'-corrections to flux induced potentials, JHEP 0206 (2002) 060, hep-th/0204254 ; A. Westphal, de Sitter string vacua from Kahler uplifting, JHEP 0703 (2007) 102, hep-th/0611332 ; V. Balasubramanian, P. Berglund, Stringy corrections to Kahler potentials, SUSY breaking, and the cosmological constant problem, JHEP 0411 (2004) 085, hep-th/0408054 ].

Y. Zinoviev

In this paper we extend our recent results (hep-th/0304067) on the first order formulation for the massless mixed symmetry tensor fields to the case of massive fields both in Minkowski as well as in (Anti) de Sitter spaces (including all possible massless and partially massless limits). Main physical results are essentially the same as in hep-th/0211233.

A. Alexandrov, A. Mironov, A. Morozov

Following the program, proposed in hep-th/0310113, of systematizing known properties of matrix model partition functions (defined as solutions to the Virasoro-like sets of linear differential equations), we proceed to consideration of non-Gaussian phases of the Hermitian one-matrix model. A unified approach is proposed for description of "connected correlators" in the form of the phase-independent "check-operators" acting on the small space of T-variables (which parametrize the polynomial W(z)). With appropriate definitions and ordering prescriptions, the multidensity check-operators look very similar to the Gaussian case (however, a reliable proof of suggested explicit expressions in all loops is not yet available, only certain consistency checks are performed).

C. Ahn

We present the configurations of intersecting branes in type IIA string theory corresponding to the meta-stable supersymmetry breaking vacua (Amariti, Girardello and Mariotti 2006 J. High Energy Phys. JHEP12(2006)058 (Preprint hep-th/0608063)) in the four-dimensional supersymmetric Yang–Mills-theory-coupled massive flavours with adjoint matter where the superpotential has three deformed terms.

I. Buchbinder, E. Ivanov

Using the ${\cal N}=2$ superfield approach, we construct full ${\cal N}=4$ supersymmetric low-energy effective actions for ${\cal N}=4$ SYM models, with both ${\cal N}=2$ gauge superfield strengths and hypermultiplet superfields included. The basic idea is to complete the known non-holomorphic effective potentials which depend only on ${\cal N}=2$ superfield strengths $W$ and ${\bar W}$ to the full on-shell ${\cal N}=4$ invariants by adding the appropriate superfield hypermultiplet terms. We prove that the effective potentials of the form ${ln} W {ln} \bar W$ can be ${\cal N} = 4$ completed in this way and present the precise structure of the corresponding completions. However, the effective potentials of the non-logarithmic form suggested in hep-th/9811017 and hep-th/9909020 do not admit the ${\cal N}=4$ completion. Therefore, such potentials cannot come out as (perturbative or non-perturbative) quantum corrections in ${\cal N}=4$ SYM models.

D. Belov, G. Moore

This paper continues the discussion of hep-th/0605038, applying the holographic formulation of self-dual theory to the Ramond-Ramond fields of type II supergravity. We formulate the RR partition function, in the presence of nontrivial H-fields, in terms of the wavefunction of an 11-dimensional Chern-Simons theory. Using the methods of hep-th/0605038 we show how to formulate an action principle for the RR fields of both type IIA and type IIB supergravity, in the presence of RR current. We find a new topological restriction on consistent backgrounds of type IIA supergravity, namely the fourth Wu class must have a lift to the H-twisted cohomology.

D. Belov

We explicitly find the spectrum of the operators $M^{rs}$ and $\widetilde{M}^{rs}$, which specify the star-product in the matter and ghost sectors correspondingly. Further we derive the diagonal representation for the 3-string vertices. Using this representation we identify the appearing Moyal structures in the matter sector. In addition to the continuous non-commutativity parameter $\theta(\kappa)$ found in hep-th/0202087 we find the discrete non-commutativity parametrized by $\theta_{\xi}$.

Ahmad Ghodsi, A. E. Mosaffa, O. Saremi et al.

Abstract In this paper we elaborate on the correspondence between the quantum Hall system with filling factor equal to one and the N = 4 SYM theory in the 1 / 2 BPS sector, previously mentioned in the [ hep-th/0409174 , hep-th/0409115 ]. We show the equivalence of the two in various formulations of the quantum Hall physics. We present an extension of the non-commutative Chern–Simons matrix theory which contains independent degrees of freedom (fields) for particles and quasiholes. The BPS configurations of our model, which is a model with explicit particle–quasihole symmetry, are in one-to-one correspondence with the 1 / 2 BPS states in the N = 4 SYM. Within our model we shed light on some less clear aspects of the physics of the N = 4 theory in the 1 / 2 BPS sector, like the giant–dual-giant symmetry, stability of the giant gravitons, and stringy exclusion principle and possible implications of the (fractional) quantum Hall effect for the AdS/CFT correspondence.