Shoichi Kawamoto

Unruh effect and holography

Abstract We study the Unruh effect on the dynamics of quarks and mesons in the context of AdS 5 /CFT 4 correspondence. We adopt an AdS 5 metric with the boundary Rindler horizon extending into a bulk Rindler-like horizon, which yields the thermodynamics with Unruh temperature verified by computing the boundary stress tensor. We then embed in it a probe fundamental string and a D7 brane in such a way that they become the dual of an accelerated quark and a meson in Minkowski space, respectively. Using the standard procedure of holographic renormalization, we calculate the chiral condensate, and also the spectral functions for both the accelerated quark and meson. Especially, we extract the corresponding strength of random force of the Langevin dynamics and observe that it can characterize the phase transition of meson melting. This result raises an issue toward a formulation of complementarity principle for the Rindler horizon. We find most of the dynamical features are qualitatively similar to the ones in the thermal bath dual to the AdS black hole background, though they could be quite different quantitatively.

Dynamical Instability of Holographic QCD at Finite Density

In this paper we study the dynamical instability of Sakai-Sugimotos holographic QCD model at finite baryon density. In this model, the baryon density, represented by the smeared instanton on the world volume of the probe D8-D8 mesonic brane, sources the world-volume electric field, and through the Chern-Simons term it will induce the instability to form a chiral helical wave at sufficient high density. Our results show that this kind of instability occurs for sufficiently high baryon number densities. The phase diagram of holographic QCD will thus be changed from the one which is based only on thermodynamics.

Branes from a non-Abelian (2,0) tensor multiplet with 3-algebra

We study the equations of motion for non-Abelian N = (2,0) tensor multiplets in six dimensions, which are recently proposed by Lambert and Papageorgakis. Some equations are regarded as constraint equations. We employ the loop algebraic extension of the Lorentzian three algebra and examine the equations of motion around various solutions to the constraint equations. The resultant equations take the forms that admit Lagrangian descriptions. Likewise the M2-brane case, we find various 5 + d dimensional Lagrangians for various branes, and we investigate relations among them from the viewpoint of the M-theory duality.

Existence of new nonlocal field theory on noncommutative space and spiral flow in renormalization group analysis of matrix models

A bstractIn the previous study [1–3], we formulate a matrix model renormalization group based on the fuzzy spherical harmonics with which a notion of high/low energy can be attributed to matrix elements, and show that it exhibits locality and various similarity to the usual Wilsonian renormalization group of quantum field theory. In this work, we continue the renormalization group analysis of a matrix model with emphasis on nonlocal interactions where the fields on antipodal points are coupled. They are indeed generated in the renormalization group procedure and are tightly related to the noncommutative nature of the geometry. We aim at formulating renormalization group equations including such nonlocal interactions and finding existence of nontrivial field theory with antipodal interactions on the fuzzy sphere. We find several nontrivial fixed points and calculate the scaling dimensions associated with them. We also consider the noncommutative plane limit and then no consistent fixed point is found. This contrast between the fuzzy sphere limit and the noncommutative plane limit would be manifestation in our formalism of the claim given by Chu, Madore and Steinacker that the former does not have UV/IR mixing, while the latter does.

Boundary condition for a D-brane from the wilson loop, and gravitational interpretation of an eigenvalue in the matrix model in ADS/CFT correspondence

We study the supersymmetric Wilson loops in the four-dimensional N=4 super Yang-Mills theory in the context of AdS/CFT correspondence. In the gauge theory side, it is known that the expectation value of the Wilson loops of circular shape with winding number k, W{sub k}(C), is calculable by using a Gaussian matrix model. In the gravity side, the expectation value of the loop is conjectured to be given by the classical value of the action S{sub D3} for a probe D3-brane with k electric fluxes as =e{sup -S{sub D3}}. Given such correspondence, we pursue the interpretation of the matrix model eigenvalue density, or more precisely the resolvent, from the viewpoint of the probe D3-brane. We see that the position of an eigenvalue appears as the gauge field plus the scalar field integrated over the boundary of the probe D3-brane. In the course of our analysis, we also clarify the boundary condition on the D3-brane in terms of the Wilson loop.

Renormalization group approach to matrix models via noncommutative space

A bstractWe develop a new renormalization group approach to the large-N limit of matrix models. It has been proposed that a procedure, in which a matrix model of size (N − 1) × (N − 1) is obtained by integrating out one row and column of an N × N matrix model, can be regarded as a renormalization group and that its fixed point reveals critical behavior in the large-N limit. We instead utilize the fuzzy sphere structure based on which we construct a new map (renormalization group) from N × N matrix model to that of rank N − 1. Our renormalization group has great advantage of being a nice analog of the standard renormalization group in field theory. It is naturally endowed with the concept of high/low energy, and consequently it is in a sense local and admits derivative expansions in the space of matrices. In construction we also find that our renormalization in general generates multi-trace operators, and that nonplanar diagrams yield a nonlocal operation on a matrix, whose action is to transport the matrix to the antipode on the sphere. Furthermore the noncommutativity of the fuzzy sphere is renormalized in our formalism. We then analyze our renormalization group equation, and Gaussian and nontrivial fixed points are found. We further clarify how to read off scaling dimensions from our renormalization group equation. Finally the critical exponent of the model of two-dimensional gravity based on our formalism is examined.

Holographic anyons in the ABJM theory

We consider the holographic anyons in the ABJM theory from three different aspects of AdS/CFT correspondence. First, we identify the holographic anyons by using the field equations of supergravity, including the Chern-Simons terms of the probe branes. We find that the composite of Dp-branes wrapped over CP3 with the worldvolume magnetic fields can be the anyons. Next, we discuss the possible candidates of the dual anyonic operators on the CFT side, and find the agreement of their anyonic phases with the supergravity analysis. Finally, we try to construct the brane profile for the holographic anyons by solving the equations of motion and Killing spinor equations for the embedding profile of the wrapped branes. As a by product, we find a BPS spiky brane for the dual baryons in the ABJM theory.

A Renormalization Group Approach to A Yang-Mills Two Matrix Model

Abstract A Yang–Mills type two matrix model with mass terms is studied by use of a matrix renormalization group approach proposed by Brezin and Zinn-Justin. The renormalization group method indicates that the model exhibits a critical behavior similar to that of two-dimensional Euclidean gravity. A massless limit and the generation of quadratic terms along the renormalization group flow are discussed.

To see Symmetry in a Forest of Trees

Abstract The exact symmetry identities among four-point tree-level amplitudes of bosonic open string theory as derived by G.W. Moore are re-examined. The main focuses of this work are: (1) Explicit construction of kinematic configurations and a new polarization basis for the scattering processes. These setups simplify greatly the functional forms of the exact symmetry identities, and help us to extract easily high-energy limits of stringy amplitudes appearing in the exact identities. (2) Connection and comparison between D.J. Grosss high-energy stringy symmetry and the exact symmetry identities as derived by G.W. Moore. (3) Observation of symmetry patterns of stringy amplitudes with respect to the order of energy dependence in scattering amplitudes.

LARGE-N RENORMALIZATION GROUP ON FUZZY SPHERE

We study the large-N renormalization group of scalar field theory on a fuzzy sphere. We carry out perturbative analysis and formulate the renormalization group equation. We then search for fixed points and investigate their properties.