121911984
Hydrodynamic Constants from Cosmic Censorship
We study a gravity dual of Bjorken flow of N = 4 SYM-theory plasma. We point out that the cosmic censorship hypothesis may explain why the regularity of the dual geometry constrains the hydrodynamic constants. We also investigate the apparent horizon of the dual geometry. We find that the dual geometry constructed on Fefferman-Graham (FG) coordinates is not appropriate for examination of the apparent horizon since the coordinates do not cover the trapped region. However, the preliminary analysis on FG coordinates suggests that the location of the apparent horizon is very sensitive to the hydrodynamic parameters.
117758947
OFF-SHELL BOUNDARY/CROSSCAP STATES AND ORIENTIFOLD PLANES ∗
It is well-known that extending string theory off-shell is a hard problem. In the first quantized string theory based on an action of a single string, the guiding principle is a local Weyl invariance of string worldsheets. This immediately translates into on-shellness of string scattering amplitudes. Off-shellness alone does not suggest any particular symmetry and one has to consider insertions of operators carrying dimensions of arbitrarily high degrees on the bulk of the string worldsheets: this is a hard task to carry out. Situation can be more manageable to handle if the local Weyl invariance is broken only on the boundaries of the worldsheets. To date there are two proposals for off-shell string theory through deformation on the boundary of the string worldsheets. The one is the boundary string field theory (BSFT) of Witten [1] on a unit disc and the other is the sigma model approach of open strings to the spacetime action S. (See for example Ref. [2] and the references therein.) To put simply,
119155440
Holographic Mean-Field Theory for Baryon Many-Body Systems
We propose a new mean-field approach to analyze many-body systems of fermions in the gauge/gravity duality. We introduce a non-vanishing classical fermionic field in the gravity dual, which we call the holographic mean field. The holographic mean field reflects the dynamics of the fermions in the bulk, and generates the expectation values of the bi-linear operators of the boundary fermions. This enables us to analyze finite-density systems of baryons in the confinement phase. Our method provides a new bulk condition which relates the chemical potential to the charge density in the GKP-Witten prescription. Many-body physics of strongly-correlated fermions is one of the central subjects in modern physics. Stronglycorrelated fermions appear in various places, such as the systems of cold atoms, high-Tc superconductors, neutron stars and the quark-gluon plasma. However, the theoretical description of many-body systems of stronglycorrelated fermions is still a challenge owing to their non-perturbative natures. One of the successful computational frameworks for strongly-interacting fermions is the lattice gauge theory, but the Monte Carlo simulation at finite baryon density suffers from the sign problem. Recently, a great deal of attention has been paid to the AdS/CFT correspondence [1–3] or the holographic method because of its ability for non-perturbative computations and the absence of the sign problem. However, the current framework of the AdS/CFT correspondence still has room for improvement in dealing with the systems at finite baryon density, as we will explain later. It can be summarized as follows: 1) dynamical baryons at finite density have not been satisfactorily incorporated, and 2) the application of the GKP-Witten prescription [2, 3] to relate the baryon chemical potential to the baryon density has an ambiguity in the grand canonical ensemble. In the present paper, we shall propose a new approach, a holographic mean-field theory for fermions, to resolve these two problems. The self-consistent incorporation of dynamical baryons in our mean-field approach provides an eigenvalue equation which eliminates the ambiguity. We shall revisit the details of these problems below. The quarks are realized as fundamental strings attached to the flavor brane in the gravity dual [4]. Each end point of the strings carries a unit charge with respect to a U(1) gauge field on the flavor brane, and the quark density can be evaluated from the electric field in the radial direction at the boundary through the Gausslaw constraint. The quark chemical potential is thus the time component of the U(1) vector potential, A0, at the boundary, which is conjugate to the electric field [5, 6]. This fits the conventional GKP-Witten prescription: The boundary value of A0 gives the source (the chemical potential); the expectation value of the conjugate operator (the density) is given by the derivative of A0 at the boundary with respect to the radial direction. These quantities are boundary conditions for the Gauss-law constraint which may be chosen arbitrarily. However, another physical condition in the bulk, i.e., the bulk condition, fixes the ambiguity in the relationship between them whenever the GKP-Witten prescription works. To the best of the authors’ knowledge, only the example where the bulk condition is yet to be known is the finite density systems of baryons.
18510901
A holographic dual of hydrodynamics
We consider a gravity dual description of time dependent, strongly interacting large-Nc = 4 SYM. We regard the gauge theory system as a fluid with shear viscosity. Our fluid is expanding in one direction following the Bjorken's picture that is relevant to RHIC experiments. We obtain the dual geometry at the late time that is consistent with dissipative hydrodynamics. We show that the integration constants that cannot be determined by hydrodynamics are given by looking at the horizon of the dual geometry. Relationship between time dependence of the energy density and bulk singularity is also discussed.
31657279
Gravity dual of spatially modulated phase
We show that the five-dimensional Maxwell theory with the Chern-Simons term is tachyonic in the presence of a constant electric field. When coupled to gravity, a sufficiently large Chern-Simons coupling causes instability of the Reissner-Nordstrom black holes in anti-de Sitter space. The instability happens only at nonvanishing momenta, suggesting a spatially modulated phase in the holographically dual quantum field theory in (3+1) dimensions, with spontaneous current generation in a helical configuration. The three-charge extremal black hole in the type IIB superstring theory on AdS_5×S^5 barely satisfies the stability condition.
124769063
Holographic Mean-Field Theory for Baryon Many-Body Systems
117947270
Meson spectroscopy with unitary coupled-channels model for heavy-meson decay into three mesons
We develop a model for describing excited mesons decay into three mesons. The properties of the excited mesons can be extracted with this model. The model maintains the three-body unitarity that has been missed in previous data analyses based on the conventional isobar models. We study an importance of the three-body unitarity in extracting hadron properties from data. For this purpose, we use the unitary and isobar models to analyze the same pseudo data of gamma p -> pi+pi+pi-n, and extract the properties of excited mesons. We find a significant difference between the unitary and isobar models in the extracted properties of excited mesons, such as the mass, width and coupling strength to decay channels.
14437805
Consideration of nuclear forces from the viewpoint of the renormalization group: Relation of nuclear forces between phenomenological approach and nuclear effective field theory
A relation between nuclear forces derived using a phenomenological approach and nuclear effective field theory (NEFT) is proposed from a renormalization group point of view. A phenomenological nuclear force (V ph ) and an NEFT-based NN-potential (V EFT ) are satisfactorily related to each other through the Wilsonian renormalization group (WRG) method. It is clearly shown that use of the simple contact interactions in NEFT is adequate to simulate small scale phenomena, and that an NEFT-based NN-potential (V EFT ) is free from dependence on the model used to describe small scale phenomena. We study the characteristics of V EFT from a WRG point of view, emphasizing points that have not previously been fully recognized. We also use the V low k method and a unitary transformation method to relate V ph to V EFT . It is found that they are not appropriate for this purpose.
118487263
Effect of three‐pion unitarity on resonance poles from heavy meson decays
We study the final state interaction in 3π decay of meson resonances at the Excited Baryon Analysis Center (EBAC) of JLab. We apply the dynamical coupled‐channels formulation which has been extensively used by EBAC to extract N* information. The formulation satisfies the 3π unitarity condition which has been missed in the existing works with the isobar models. We report the effect of the 3π unitarity on the meson resonance pole positions and Dalitz plot.
1110514
Renormalization group analysis of nuclear force
We study a relation between nuclear forces based on phenomenological approach ( V ph ) and nuclear effective field theory ( V EFT ) from a viewpoint of renormalization group. We find the relation between these two types of nuclear force using Wilsonian renormalization group equation. Considering the fact that V EFT is defined in a certain small model space, we show that a simple contact interaction accurately simulates short-distance physics, and that V EFT is free from dependence on modelling the details of the short-distance physics. Based on our result, we discuss some features of nuclear effective field theory.
85451103
Extraction of Meson Resonances from Three-pions Photo-production Reactions
We have investigated the model dependence of meson resonance properties extracted from the Dalitz-plot analysis of the three-pions photoproduction reactions on the nucleon. Within a unitary model developed in Phys. Rev. D 84, 114019 (2011), we generate Dalitz-plot distributions as data to perform an isobar model fit that is similar to most of the previous analyses of three-pion production reactions. It is found that the resonance positions from the two models agree well when both fit the data accurately, except for the resonance poles near branch points. The residues of the resonant amplitudes extracted from the two models and by the usual Breit-Wigner procedure agree well only for the isolated resonances with narrow widths. For overlapping resonances, most of the extracted residues could be drastically different. Our results suggest that even with high precision data, the resonance extraction should be based on models within which the amplitude parametrization is constrained by three-particle unitarity condition.