Speaker：Takao Suyama (Seoul Natl. U.)

Abstract:
We investigate BPS Wilson loops in ABJM theory. The Wilson loop operators are explicitly constructed. A conjecture on the relation of them to the fundamental string in the bulk is proposed. The vev of the Wilson loop is evaluated perturbatively, and its exact form is argued.

Speaker：Kyosuke Hotta (Osaka Univ.)

Abstract:
We present a new exact black hole solution in three dimensional Einstein gravity coupled to a single scalar field. This is one of the extended solutions of the BTZ black hole and has in fact AdS_3 geometries both at the spatial infinity and at the event horizon. An explicit derivation of Virasoro algebras for CFT_2 at the two boundaries is shown to be possible a la Brown and Henneaux's calculation. If we regard the scalar field as a running coupling in the dual two dimensional field theory, and its flow in the bulk as the ``holographic" renormalization group flow, our black hole should interpolate the two CFT_2 living at the infinity and at the horizon. Following the Hamilton-Jacobi analysis by de Boer, Verlinde and Verlinde, we calculate the central charges c_{UV} and c_{IR} for the CFT_2 on the infinity and the horizon, respectively. We also confirm that the inequality c_{IR} < c_{UV} is satisfied, which is consistent with the Zamolodchikov's c-theorem.

Reference: 0811.0910, 0902.3529

Speaker：Kentaro Hanaki (Univ. of Michigan)
Abstract：
The bound for the shear viscosity to entropy density ratio, proposed by Kovtun, Son and Starinets (KSS) utilizing the celebrated AdS/CFT correspondence, is satisfied for all known substances in nature. This is of particular interest as this is the first "prediction" string theory made to real world physics. After reviewing how to calculate shear viscosity and entropy density for gauge theory plasma in the gravity dual perspective, I will discuss the finite N corrections to the bound with and without chemical potential.

Speaker：Yosuke Imamura (Univ. of Tokyo, Hongo)

Abstract:
We discuss AdS/CFT duality between N=4 Chern-Simons theories, which are realized on M2-branes in certain orbifold backgrounds, and their gravity duals. We mainly focus on the field/operator correspondence, and argue the role of monopole operators in the correspondence.

Speaker：Masato Arai (CQUeST, Sogang U.)

Abstract:
We construct the classical action of the Ahanony-Bergman-Jafferis-Maldacena (ABJM) model in the N=4 d=3 projective superspace (PSS), but only for Abelian case. The superfield action consists of the kinetic term of two hypermultiplets with minimal gauge interactions and two Chern-Simon terms corresponding to two gauge groups. In this construction, we derive the Abelian Chern-Simon term in PSS for the first time. We also discuss problems in an extension into non-Abelian case. (It may be changed according to progress.)

Speaker：Shinji Mukohyama (IPMU)

Abstract:
Based on the renormalizable theory of gravitation recently proposed by Horava, we present a simple scenario to generate almost scale-invariant, super-horizon curvature perturbations. The anisotropic scaling with dynamical critical exponent z=3 implies that the amplitude of quantum fluctuations of a free scalar field generated in the early epoch of the expanding universe is insensitive to the Hubble expansion rate and, thus, scale-invariant. Those fluctuations are later converted to curvature perturbations by the curvaton mechanism or/and the modulated decay of heavy particles/oscillating fields. This scenario works, for example, for power law expansion a\propto t^p with p>1/3 and, thus, does not require inflation. Also, this scenario does not rely on any additional assumptions such as the detailed balance condition.

Speaker：So Matsuura (Keio Univ.)

Abstract:
In this talk, we consider the Hanany-Witten type brane configuration in a RR 4-form background and examine the behavior of Euclidean D0-branes propagating between two NS5-branes. We show that the partition function of the D0-branes coincides with the Nekrasov partition function of instantons for four-dimensional N=2 supersymmetric Yang-Mills theory. We also apply the same method to N=2 SQCD.

Speaker：Shotaro Shiba (Univ. of Tokyo, Hongo)

Abstract:
BLG (Bagger-Lambert-Gustavsson) model is considered as the theory which describes the multiple M2-branes in M-theory. Its action is distinctive in that the gauge symmetry is based on Lie 3-algebra. As an example of this algebra, we can adopt one which includes (ordinary) Lie algebras and loop algebras. BLG model with such an algebra, however, becomes the multiple Dp-branes theory in type IIA or IIB superstring theory, instead of M-theory. In this seminar, I will explain on these topics and discuss the duality of M-theory and superstring theory in BLG models.

Reference: 0901.2003[hep-th]

Speaker：Yasuyuki Hatsuda (Riken)

Abstract:
Integrability has shed light on the spectrum of the planar AdS/CFT correspondence. Recently finite-size corrections of the spectrum are investigated. In this talk, I will give a review on some recent developments of the AdS/CFT spectrum, and explain how to analyze the finite-size corrections of strings called giant magnons.

Speaker：Isao Kishimoto (Riken)

Abstract:
We explore vacuum structure in bosonic open string field theory expanded around an identity based solution parameterized by a (>= -1/2). Analyzing the expanded theory by using level truncation approximation, we find that the theory has a stable vacuum solution for a>-1/2. The vacuum energy and the gauge invariant overlap numerically approach those of the tachyon vacuum solution with increasing truncation level. Also we find that, at a=-1/2, there exists an unstable vacuum solution in the expanded theory and it rapidly becomes the trivial zero configuration just above a=-1/2. The numerical behavior of the two gauge invariants suggests that the unstable solution corresponds to the perturbative open string vacuum. These results reasonably support the expectation that the identity based solution is a trivial pure gauge configuration for a>-1/2, but it can be regarded as the tachyon vacuum solution at a=-1/2.

Reference: 0904.1095[hep-th]

Speaker：Tetsuji Kimura (KEK)

Abstract:
We consider flux vacua attractor equations in type IIA string theory compactified on generalized geometries with orientifold projections. The four-dimensional N=1 superpotential in this compactification can be written as the sum of the Ramond-Ramond superpotential and a term described by (non)geometric flux charges. We exhibit a simple model in which supersymmetric AdS and Minkowski solutions are classified by means of discriminants of the two superpotentials. We further study various configurations without Ramond-Ramond flux charges. In this case we find supersymmetric AdS vacua both in the case of compactifications on generalized geometries with SU(3) x SU(3) structures and on manifolds with an SU(3)-structure without nongeometric flux charges. In the latter case, we have to introduce correction terms into the prepotential in order to realize consistent vacua. 　

Reference:0810.0937[hep-th]

Speaker：Shun'ya Mizoguchi (KEK)

Abstract:
Using intersecting E8 x E8 heterotic 5-branes, we propose a new, extremely simple model for string compactification scenario which may naturally explain, among other things, why there are three generations of elementary particles in Nature. A key role is played by Nambu-Goldstone modes (moduli) supported on the intersection. By compactifying one of the transverse dimensions on S1, we obtain a Randall-Sundrum-like model in heterotic string theory without cosmological constant. This enables us to realize a three-flavor E6 GUT model in the framework of gauge-Higgs unification. Phrased differently, the prediction made by Kobayashi-Maskawa is naturally, though unexpectedly, fulfilled by Nambu-Goldstone modes on branes in heterotic string theory.

Speaker：Kin-ya Oda (Osaka U.)

Abstract:
We reveal natures of relativistically expanding plasma through a time-dependent black hole. The Quark-Gluon Plasma (QGP) is a new state of matter whose internal friction (viscosity-to-entropy ratio) has recently been observed to be far smaller than any other known fluids. Such a tiny internal friction indicates extremely strong interactions among the constituents of the QGP, quarks and gluons. Since the universe was once made of the strongly-interacting QGP, it is important to build a theory that can account for its behaviors, in order to deepen our knowledge on the Big Bang. Theoretical (microscopic) description of the QGP is one of the biggest challenges in physics due to its very strong interaction. A breakthrough came from superstring theory which suggests that a certain strongly-interacting system, similar to the QGP, is mathematically equivalent to a five-dimensional black hole. However, previous attempts on a time-dependent system have suffered from an appearance of divergence (naked singularity). We have succeeded, for the first time, to construct a consistent time-dependent black hole that can completely account for the relativistic flow of the QGP-like fluid. We have proven that all the possible divergences are safely hidden by a time-dependent horizon (from which no signals can escape). This work provides a basis to treat a time-dependent system from both the microscopic and macroscopic points of view simultaneously.

Reference: Phys. Rev. Lett. 102, 031601 (2009) [arXiv:0901.4834 [hep-th]], Prog. Theor. Phys. 121, 121 (2009) [arXiv:0807.3797 [hep-th]].

Speaker：Masato Arai (CQUeST, Sogang U.)

Abstract: The Bogomol'nyi-Prasad-Sommerfield (BPS) multiwall solutions are constructed in a massive Kahler nonlinear sigma model on the complex quadric surface, Q^N=SO(N+2)/[SO(N)\times SO(2)] in 3-dimensional space-time. The theory has a non-trivial scalar potential generated by the Scherk-Schwarz dimensional reduction from the massless nonlinear sigma model on Q^N in 4-dimensional space-time and it gives rise to 2[N/2+1] discrete vacua. The BPS wall solutions connecting these vacua are obtained based on the moduli matrix approach. It is also shown that the moduli space of the BPS wall solutions is the complex quadric surface Q^N.

Reference: arXiv:0908.3713.

Speaker：Kazunobu Maruyoshi (YITP)

Abstract:
We propose a number of new Seiberg dualities of N=1 quiver gauge theories. The new Seiberg dualities originate in new S-dualities of N=2 superconformal field theories recently proposed by Gaiotto. N=2 S-dual theories deformed by suitable mass terms flow to our N=1 Seiberg dual theories. We show that the number of exactly marginal operators is universal for these Seiberg dual theories and the 't Hooft anomaly matching holds for these theories. These provide strong evidence for the new Seiberg dualities. Furthermore, we study in detail the Klebanov-Witten type theory and its dual as a concrete example. We show that chiral operators and their non-linear relations match between these theories. These arguments also give non-trivial consistency checks for our proposal. This talk is based on the collaboration with M. Taki, S. Terashima and F. Yagi.

Reference: arXiv:0907.2625[hep-th]

Speaker：Shuichi Yokoyama (Univ. of Tokyo, Hongo)

Abstract:
We computed a Witten-type index for N=4 Chern-Simons theories with gauge group U(N)^r in the large N limit with taking account of monopole contribution, and compared it to the multiparticle index for M-theory in the dual geometry AdS_4 x X_7. The internal space X_7 in the dual geometry has b_2(X_7)(=r-2) non-trivial two-cycles, and M2-branes wrapped on them contribute to the multi-particle index. We established one-to-one correspondences as follows: between the fivebrane linking numbers and the Wilson lines on the singular loci, and between the diagonal magnetic charge and the M-momentum, and between r-2 independent magnetic charges and b_2(X_7) wrapping numbers. This claim is supported by the perfect agreement of the indices for both sides in many sectors by using analytic and numerical methods. These results strongly suggests that monopole operators correspond to M2-branes wrapped on the two-cycles.

Reference: Y.~Imamura and S.~Yokoyama, ``A Monopole Index for N=4 Chern-Simons Theories,'' arXiv:0908.0988 [hep-th].
Y.~Imamura and S.~Yokoyama, ``N=4 Chern-Simons theories and wrapped M5-branes in their gravity duals,'' Prog. Theor. Phys. 121, 915 (2009) [arXiv:0812.1331 [hep-th]].
J.~Bhattacharya, S.~Bhattacharyya, S.~Minwalla and S.~Raju, ``Indices for Superconformal Field Theories in 3,5 and 6 Dimensions,'' JHEP {¥bf 0802}, 064 (2008) [arXiv:0801.1435 [hep-th]].
S.~Kim, ``The complete superconformal index for N=6 Chern-Simons theory,'' Nucl.¥ Phys.¥ B {¥bf 821}, 241 (2009) [arXiv:0903.4172 [hep-th]].

Speaker：Andrei Marshakov (Lededev Physics Institute and ITEP)

Abstract:
I discuss the Seiberg-Witten prepotentials for N=2 supersymmetric four-dimensional QCD and their deformed versions - the Nekrasov instanton partition functions. The latter are expressed in terms of correlation functions in two-dimensional conformal theories. This 4d/2d duality (recently revived by Alday, Gaiotto and Tachikawa) leads to exact formula the for nontrivial instantonic renormalization of coupling in 4d conformal QCD and expresses instantonic corrections in the asymptotically-free Yang-Mills theories directly in terms of the scalar products of the 2d Virasoro descendants.

Speaker：Nick Manton (Univ. Cambridge)

Abstract:
Effective field theories of pions have topological soliton solutions called Skyrmions, whose topological charge can be identified with baryon number. When quantized, the Skyrmions acquire spin and isospin quantum numbers. In this talk I will review what is known about classical Skyrmion solutions for baryon numbers 1 up to 16 and beyond. I will also discuss the ground and excited quantum states of Skyrmions, and compare these to experimentally determined nuclear spectra, including those of beryllium-8 and carbon-12, and their isobars. The results give a field-theoretic insight into cluster models of nuclei, and especially the well-known alpha-particle model of nuclei.

Reference: R.A. Battye, N.S. Manton, P.M. Sutcliffe and S.W. Wood, Light nuclei of even mass number in the Skyrme model, arXiv:0905.0099 [nucl-th] (to appear in Phy. Rev. C).

Speaker：Seiji Terashima (YITP)

Abstract:
We construct a new classical solution in the ABJM theory corresponding to M5-branes with a non-zero self-dual three form flux. This is an M-theory lift of the D4-brane solution expressed as a non-commutative plane in the three dimensional super Yang-Mills theory. We discuss that our solution is closely related with the three-algebra. We show that the corresponding configuration of the M5-brane satisfies the equations of motion in the single M5-brane action. We find the agreement between the tension of the M5-brane solution in the ABJM action and the one computed from the single M5-brane action.

Reference: Seiji Terashima and Futoshi Yagi, arXiv:0909.3101.

Speaker：Etsuko Itou (Kogakuin Univ)

Abstract:
We present a non-perturbative study of the running coupling constant for SU(3) gauge theories within lattice simulations. We investigate how the systematic and statistical errors can be controlled {\it via} a feasibility study in SU(3) pure Yang-Mills theory using Twisted Polyakov Loop scheme. We show that our method reproduces the perturbative determination of the running coupling in the UV. In addition, our numerical result agrees with the theoretical prediction of this coupling constant in the IR. We also present our preliminary results for $N_f=12$ QCD, where an IR fixed point may be present.

Reference: E. Bilgici et al. arXiv:0910.4196v1
T. Appelquist, G. T. Fleming, E. T. Neil, Phys.Rev.D79:076010,2009.

Speaker：Teruhiko Kawano (Univ. of Tokyo, Hongo)

Abstract:
After a brief review on F-theory compactifications, how the flavor structure of grand unified models in F-theory comoactifications can be achieved will be discussed.

Reference: arXiv:0910.2762.

Speaker：Yoshifumi Hyakutake (KEK)

Abstract:
One of the powerful techniques in string theory is gauge/gravity correspondence which enables us to study strong coupling region of the gauge theory. In this talk, I will investigate the gauge/gravity correspondence including higher derivative corrections in string theory and M-thoery. First I derive the higher derivative corrections in string theory and M-theory by imposing local supersymmetry. Then I will apply these corrections to the black 0-brane thermodynamics and AdS3/CFT2 correspondence in topologically massive gravity. These results indicate that the gauge/gravity correspondence holds including higher derivative corrections.

Reference: arXiv:0811.3102, PRL 102 (2009) 191602, with M. Hanada, J. Nishimura and S. Takeuchi; arXiv:0805.2005,JHEP 0807:066, arXiv:0906.1255, PLB 680 (2009), with K. Hotta, T. Kubota T. Nishinaka and H. Tanida; hep-th/0703154, PTP 118 No.1 (2007), etc.

Speaker：Shin Nakamura (Kyoto Univ.)

Abstract:
Although many interesting phenomena are expected to occur at finite baryon densities in QCD, there is a technical difficulty in Lattice QCD to analyze finite baryon density systems. In the gauge/gravity correspondence, a good testing ground for finite density systems is asymptotically AdS 5d Reissner-Nordstrom black hole (RN-AdS BH), which is a solution to the 5d Einstein-Maxwell equations. However, if we ask the origin of the 5d theory to the 10d type IIB supergravity (SUGRA), we need to add a Chern-Simons (CS) term to the 5d Einstein-Maxwell theory. We point out that the CS term modifies the spectrum of the bulk degree of freedom, and some fluctuations around the RN-AdS BH become tachyonic if the CS coupling is greater than some critical value. The instability occurs only at finite momenta, meaning that the condensation is spatially modulated and the translational/rotational symmetries are spontaneously broken. Unfortunately, the CS couplings consistent with 10d SUGRA are barely small to achieve the instability as far as the models we have checked. However, 5d Einstein-Maxwell-CS theory at large enough CS coupling can be a good phenomenological model to describe phase transitions into spatially modulated phase.

Reference: arXiv:0911.0679 Title: Gravity Dual of Spatially Modulated Phase Authors: Shin Nakamura, Hirosi Ooguri, Chang-Soon Park

Speaker：Machiko Hatsuda (KEK & Urawa U.) )

Abstract:
AdS4xCP3弦やブラックホール解において、 Hopf fibration、 Squashing 及び　Zk quotientというような幾何学的変形が重要な役割を担っている。これらの基本的な幾何学的変形についてシンプルなcoset定式化の導出を与える。この方法では、系の対称性を明白に扱うことができる。 Squashing は射影空間の対称性を保つような similarity変換で記述され、一方Zk quotientはトポロジーを変えるが局所的な対称性は変えない lens空間として記述される。

Reference: M.　Hatsuda and S.　Tomizawa, ``Coset for Hopf fibration and Squashing'', Class. Quant. Grav. 26 (2009) 225007, arXiv:0906.1025.

Speaker：Tatsuhiro Misumi (Yukawa Inst.)

Abstract: We investigate the finite-temperature spectral functions of heavy quarkonia by using the soft-wall AdS/QCD model. The dissociation of the meson tower onto the AdS black hole leads to the in-medium mass shift and the width broadening in a way similar to the lattice QCD results for the heavy quarkonium at finite temperature. We discuss the scalar, the pseudo-scalar, the vector, and the axial-vector mesons and compare their qualitative features of the melting temperature and growing width. We find that the axial-vector meson melts earlier than the vector meson, while there appears only a slight difference between the scalar and pseudo-scalar mesons which also melt earlier than the vector meson. We also show the momentum dependence of the spectral function and find it consistent with screening in a hot wind.

Reference: M.Fujita, K.Fukushima, T.Misumi and M.Murata, Physical Review D 80, 035001 (2009)
M.Fujita, K.Fukushima, T.Kikuchi, T.Misumi and M.Murata, arXiv:0911.2298 (2009)
Y.Kim, T.Misumi and I.J.Shin, arXiv:0911.3205 (2009)

Speaker：Yuji Tachikawa (IAS)

Abstract: A systematic method to construct N=2 supersymmetric 4d gauge theory by compactifying M5-branes on a Riemann surface was found by Gaiotto last year. It was then noted that Nekrasov's partition function, which is a two-parameter deformation of the low-energy prepotential of the gauge theory, equals the correlation function of Liouville/Toda field theory living on the Riemann surface on which M5-branes are compactified. I would like to illustrate this map through a few explicit examples.

Reference: 0906.3219, 0909.4776, 0911.4787