738 research outputs found
Holographic Confining Gauge theory and Response to Electric Field
We study the response of confining gauge theory to the external electric
field by using holographic Yang-Mills theories in the large limit.
Although the theories are in the confinement phase, we find a transition from
the insulator to the conductor phase when the electric field exceeds its
critical value. Then, the baryon number current is generated in the conductor
phase. At the same time, in this phase, the meson melting is observed through
the quasi-normal modes of meson spectrum. Possible ideas are given for the
string state corresponding to the melted mesons, and they lead to the idea that
the source of this current may be identified with the quarks and anti-quarks
supplied by the melted mesons. We also discuss about other possible carriers.
Furthermore, from the analysis of the massless quark, chiral symmetry
restoration is observed at the insulator-conductor transition point by studying
a confining theory in which the chiral symmetry is broken.Comment: 27 pages, 14 figure
Universal properties of thermal and electrical conductivity of gauge theory plasmas from holography
We propose that for conformal field theories admitting gravity duals, the
thermal conductivity is fixed by the central charges in a universal manner.
Though we do not have a proof as yet, we have checked our proposal against
several examples. This proposal, if correct, allows us to express electrical
conductivity in terms of thermodynamical quantities even in the presence of
chemical potential.Comment: 13 pages, appendix added, close to journal versio
Constraints on Superfluid Hydrodynamics from Equilibrium Partition Functions
Following up on recent work in the context of ordinary fluids, we study the
equilibrium partition function of a 3+1 dimensional superfluid on an arbitrary
stationary background spacetime, and with arbitrary stationary background gauge
fields, in the long wavelength expansion. We argue that this partition function
is generated by a 3 dimensional Euclidean effective action for the massless
Goldstone field. We parameterize the general form of this action at first order
in the derivative expansion. We demonstrate that the constitutive relations of
relativistic superfluid hydrodynamics are significantly constrained by the
requirement of consistency with such an effective action. At first order in the
derivative expansion we demonstrate that the resultant constraints on
constitutive relations coincide precisely with the equalities between
hydrodynamical transport coefficients recently derived from the second law of
thermodynamics.Comment: 46 page
A note on conductivity and charge diffusion in holographic flavour systems
We analyze the charge diffusion and conductivity in a Dp/Dq holographic setup
that is dual to a supersymmetric Yang-Mills theory in p+1 dimensions with N_f<<
N_c flavour degrees of freedom at finite temperature and nonvanishing U(1)
baryon number chemical potential. We provide a new derivation of the results
that generalize the membrane paradigm to the present context. We perform a
numerical analysis in the particular case of the D3/D7 flavor system. The
results obtained support the validity of the Einstein relation at finite
chemical potential.Comment: 15 pages, 3 figures, v2 with minor correction
The ultraviolet limit and sum rule for the shear correlator in hot Yang-Mills theory
We determine a next-to-leading order result for the correlator of the shear
stress operator in high-temperature Yang-Mills theory. The computation is
performed via an ultraviolet expansion, valid in the limit of small distances
or large momenta, and the result is used for writing operator product
expansions for the Euclidean momentum and coordinate space correlators as well
as for the Minkowskian spectral density. In addition, our results enable us to
confirm and refine a shear sum rule originally derived by Romatschke, Son and
Meyer.Comment: 16 pages, 2 figures. v2: small clarifications, one reference added,
published versio
Equation of State and Collective Dynamics
This talk summarizes the present status of a program to quantitatively relate
data from the Relativistic Heavy Ion Collider (RHIC) on collective expansion
flow to the Equation of State (EOS) of hot and dense strongly interacting
matter, including the quark-gluon plasma and the quark-hadron phase transition.
The limits reached with the present state of the art and the next steps
required to make further progress will both be discussed.Comment: 8 pages, 6 two-part figures. Invited talk given at the 5th
International Conference on the Physics and Astrophysics of Quark-Gluon
Plasma (ICPAQGP 2005), Kolkata (India), Feb 8-12, 2005. Proceedings to be
published in Journal of Physics: Conference Series (Jan-E Alam et al., eds.
Holographic RG flow of the shear viscosity to entropy density ratio in strongly coupled anisotropic plasma
We study holographic RG flow of the shear viscosity tensor of anisotropic,
strongly coupled N=4 super-Yang-Mills plasma by using its type IIB supergravity
dual in anisotropic bulk spacetime. We find that the shear viscosity tensor has
three independent components in the anisotropic bulk spacetime away from the
boundary, and one of the components has a non-trivial RG flow while the other
two have a trivial one. For the component of the shear viscosity tensor with
non-trivial RG flow, we derive its RG flow equation, and solve the equation
analytically to second order in the anisotropy parameter 'a'. We derive the RG
equation using the equation of motion, holographic Wilsonian RG method, and
Kubo's formula. All methods give the same result. Solving the equation, we find
that the ratio of the component of the shear viscosity tensor to entropy
density 'eta/s' flows from above '1/4pi' at the horizon (IR) to below '1/4pi'
at the boundary (UV) where it violates the holographic shear viscosity
(Kovtun-Son-Starinets) bound and where it agrees with the other longitudinal
component.Comment: 17 pages, 2 figures, slight change on the title, more background
material added, references added, accepted for publication in JHE
The effect of higher derivative correction on and conductivities in STU model
In this paper we study the ratio of shear viscosity to entropy, electrical
and thermal conductivities for the R-charged black hole in STU model. We
generalize previous works to the case of a black hole with three different
charges. Actually we use diffusion constant to obtain ratio of shear viscosity
to entropy. By applying the thermodynamical stability we recover previous
results. Also we investigate the effect of higher derivative corrections.Comment: revised versio
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