107 research outputs found
Gauge invariant Lagrangian for non-Abelian tensor gauge fields of fourth rank
Using generalized field strength tensors for non-Abelian tensor gauge fields
one can explicitly construct all possible Lorentz invariant quadratic forms for
rank-4 non-Abelian tensor gauge fields and demonstrate that there exist only
two linear combinations of them which form a gauge invariant Lagrangian.
Together with the previous construction of independent gauge invariant forms
for rank-2 and rank-3 tensor gauge fields this construction proves the
uniqueness of early proposed general Lagrangian up to rank-4 tensor fields.
Expression for the coefficients of the general Lagrangian is presented in a
compact form.Comment: 27 pages, LaTex fil
Density Dependence of Transport Coefficients from Holographic Hydrodynamics
We study the transport coefficients of Quark-Gluon-Plasma in finite
temperature and finite baryon density. We use AdS/QCD of charged AdS black hole
background with bulk-filling branes identifying the U(1) charge as the baryon
number. We calculate the diffusion constant, the shear viscosity and the
thermal conductivity to plot their density and temperature dependences.
Hydrodynamic relations between those are shown to hold exactly. The diffusion
constant and the shear viscosity are decreasing as a function of density for
fixed total energy. For fixed temperature, the fluid becomes less diffusible
and more viscous for larger baryon density.Comment: LaTeX, 1+33 pages, 6 figures, references adde
Sound Modes in Holographic Hydrodynamics for Charged AdS Black Hole
In the previous paper we studied the transport coefficients of Quark-Gluon
Plasma in finite temperature and finite density in vector and tensor modes. In
this paper, we extend it to the scalar modes. We work out the decoupling
problem and hydrodynamic analysis for the sound mode in charged AdS black hole
and calculate the sound velocity, the charge susceptibility and the electrical
conductivity. We find that Einstein relation among the conductivity, the
diffusion constant and the susceptibility holds exactly.Comment: 1+33 pages, 4 figures, LaTeX; references added, improved section 4.
The bosonic string and superstring models in 26+2 and 10+2 dimensional space--time, and the generalized Chern-Simons action
We have covariantized the Lagrangians of the U(1)_V * U(1)_A models, which
have U(1)_V * U(1)_A gauge symmetry in two dimensions, and studied their
symmetric structures. The special property of the U(1)_V * U(1)_A models is the
fact that all these models have an extra time coordinate in the target
space-time. The U(1)_V * U(1)_A models coupled to two-dimensional gravity are
string models in 26+2 dimensional target space-time for bosonic string and in
10+2 dimensional target space-time for superstring. Both string models have two
time coordinates. In order to construct the covariant Lagrangians of the U(1)_V
* U(1)_A models the generalized Chern-Simons term plays an important role. The
supersymmetric generalized Chern-Simons action is also proposed. The
Green-Schwarz type of U(1)_V * U(1)_A superstring model has another fermionic
local symmetry as well as \kappa-symmetry. The supersymmetry of target
space-time is different from the standard one.Comment: 27 pages, no figure
Yet Another Realization of Kerr/CFT Correspondence
The correspondence between the Kerr black hole and a boundary CFT has been
conjectured recently. The conjecture has been proposed first only for the half
of the CFT, namely for left movers. For right movers, the correspondence has
been also found out through the suitable asymptotic boundary condition.
However, the boundary conditions for these two studies are exclusive to each
other. The boundary condition for left movers does not allow the symmetry of
right movers, and vice versa. We propose new boundary condition which allows
both of left and right movers.Comment: 6 pages, references adde
Entropy Bound and Causality Violation in Higher Curvature Gravity
In any quantum theory of gravity we do expect corrections to Einstein gravity
to occur. Yet, at fundamental level, it is not apparent what the most relevant
corrections are. We argue that the generic curvature square corrections present
in lower dimensional actions of various compactified string theories provide a
natural passage between the classical and quantum realms of gravity. The
Gauss-Bonnet and gravities, in particular, provide concrete
examples in which inconsistency of a theory, such as, a violation of
microcausality, and a classical limit on black hole entropy are correlated. In
such theories the ratio of the shear viscosity to the entropy density,
, can be smaller than for a boundary conformal field theory with
Einstein gravity dual. This result is interesting from the viewpoint that the
nuclear matter or quark-gluon plasma produced (such as at RHIC) under extreme
densities and temperatures may violate the conjectured bound , {\it albeit} marginally so.Comment: 23 pages, several eps figures; minor changes, references added,
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