17,464 research outputs found
Diffusion constant of supercharge density in N=4 SYM at finite chemical potential
We compute holographically the diffusion constant of supercharges in N=4 SYM
at finite chemical potential for the R-charge, by solving the equations of
motion for the transverse mode of the gravitino in the STU black hole in 5
dimensions. We consider the case of one charge and three charges, and we
present analytical solutions for small values of the charges and numerical
solutions for arbitrary values. We compare our results with other known results
in 4 dimensions.Comment: 20 pages, 4 figures; v2: typos correcte
Shear sum rules at finite chemical potential
We derive sum rules which constrain the spectral density corresponding to the
retarded propagator of the T_{xy} component of the stress tensor for three
gravitational duals. The shear sum rule is obtained for the gravitational dual
of the N=4 Yang-Mills, theory of the M2-branes and M5-branes all at finite
chemical potential. We show that at finite chemical potential there are
additional terms in the sum rule which involve the chemical potential. These
modifications are shown to be due to the presence of scalars in the operator
product expansion of the stress tensor which have non-trivial vacuum
expectation values at finite chemical potential.Comment: The proof for the absence of branch cuts is corrected.Results
unchange
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
Spatial Correlation Analysis of the Pharmacological Conversion of Sustained Atrial Fibrillation in Conscious Goats by Cibenzoline
Sum rules and three point functions
Sum rules constraining the R-current spectral densities are derived
holographically for the case of D3-branes, M2-branes and M5-branes all at
finite chemical potentials. In each of the cases the sum rule relates a certain
integral of the spectral density over the frequency to terms which depend both
on long distance physics, hydrodynamics and short distance physics of the
theory. The terms which which depend on the short distance physics result from
the presence of certain chiral primaries in the OPE of two R-currents which are
turned on at finite chemical potential. Since these sum rules contain
information of the OPE they provide an alternate method to obtain the structure
constants of the two R-currents and the chiral primary. As a consistency check
we show that the 3 point function derived from the sum rule precisely matches
with that obtained using Witten diagrams.Comment: 41 page
Hydrodynamics from charged black branes
We extend the recent work on fluid-gravity correspondence to charged
black-branes by determining the metric duals to arbitrary charged fluid
configuration up to second order in the boundary derivative expansion. We also
derive the energy-momentum tensor and the charge current for these
configurations up to second order in the boundary derivative expansion. We find
a new term in the charge current when there is a bulk Chern-Simons interaction
thus resolving an earlier discrepancy between thermodynamics of charged
rotating black holes and boundary hydrodynamics. We have also confirmed that
all our expressions are covariant under boundary Weyl-transformations as
expected.Comment: 0+ 31 Pages; v2: 0+33 pages, typos corrected and new sections (in
appendix) added; v3:published versio
Viscosity Bound and Causality in Superfluid Plasma
It was argued by Brigante et.al that the lower bound on the ratio of the
shear viscosity to the entropy density in strongly coupled plasma is translated
into microcausality violation in the dual gravitational description. Since
transport properties of the system characterize its infrared dynamics, while
the causality of the theory is determined by its ultraviolet behavior, the
viscosity bound/microcausality link should not be applicable to theories that
undergo low temperature phase transitions. We present an explicit model of
AdS/CFT correspondence that confirms this fact.Comment: 27 pages, 5 figures. References added, typos fixe
On Semiclassical Limits of String States
We explore the relation between classical and quantum states in both open and
closed (super)strings discussing the relevance of coherent states as a
semiclassical approximation. For the closed string sector a gauge-fixing of the
residual world-sheet rigid translation symmetry of the light-cone gauge is
needed for the construction to be possible. The circular target-space loop
example is worked out explicitly.Comment: 12 page
Nonlinear Hydrodynamics from Flow of Retarded Green's Function
We study the radial flow of retarded Green's function of energy-momentum
tensor and -current of dual gauge theory in presence of generic higher
derivative terms in bulk Lagrangian. These are first order non-linear Riccati
equations. We solve these flow equations analytically and obtain second order
transport coefficients of boundary plasma. This way of computing transport
coefficients has an advantage over usual Kubo approach. The non-linear equation
turns out to be a linear first order equation when we study the Green's
function perturbatively in momentum. We consider several examples including
term and generic four derivative terms in bulk. We also study the flow
equations for -charged black holes and obtain exact expressions for second
order transport coefficients for dual plasma in presence of arbitrary chemical
potentials. Finally we obtain higher derivative corrections to second order
transport coefficients of boundary theory dual to five dimensional gauge
supergravity.Comment: Version 2, reference added, typos correcte
In-medium hadronic spectral functions through the soft-wall holographic model of QCD
We study the scalar glueball and vector meson spectral functions in a hot and
dense medium by means of the soft-wall holographic model of QCD. Finite
temperature and density effects are implemented through the AdS/RN metric. We
analyse the behaviour of the hadron masses and widths in the plane,
and compare our results with the experimental ones and with other theoretical
determinations.Comment: 16 pages, 6 figures. matching the published versio
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