10 research outputs found
Drag and jet quenching of heavy quarks in a strongly coupled N=2* plasma
The drag of a heavy quark and the jet quenching parameter are studied in the
strongly coupled N=2* plasma using the AdS/CFT correspondence. Both increase in
units of the spatial string tension as the theory departs from conformal
invariance. The description of heavy quark dynamics using a Langevin equation
is also considered. It is found that the difference between the velocity
dependent factors of the transverse and longitudinal momentum broadening of the
quark admit an interpretation in terms of relativistic effects, so the
distribution is spherical in the quark rest frame. When conformal invariance is
broken there is a broadening of the longitudinal momentum distribution. This
effect may be useful in understanding the jet distribution observed in
experiments.Comment: 30 pages, 5 figures, references added, minor corrections. To be
published in JHE
Heavy quarks in the presence of higher derivative corrections from AdS/CFT
We use the gauge-string duality to study heavy quarks in the presence of
higher derivative corrections. These corrections correspond to the finite
coupling corrections on the properties of heavy quarks in a hot plasma. In
particular, we study the effects of these corrections on the energy loss and
the dissociation length of a quark-antiquark pair. We show that the calculated
energy loss of heavy quarks through the plasma increases. We also find in
general that the dissociation length becomes shorter with the increase of
coupling parameters of higher curvature terms.Comment: 22pages, 8 figures, Revised versio
Shear viscosity, instability and the upper bound of the Gauss-Bonnet coupling constant
We compute the dimensionality dependence of for charged black branes
with Gauss-Bonnet correction. We find that both causality and stability
constrain the value of Gauss-Bonnet coupling constant to be bounded by 1/4 in
the infinite dimensionality limit. We further show that higher dimensionality
stabilize the gravitational perturbation. The stabilization of the perturbation
in higher dimensional space-time is a straightforward consequence of the
Gauss-Bonnet coupling constant bound.Comment: 16 pages,3 figures+3 tables,typos corrected, published versio
Stochastic trailing string and Langevin dynamics from AdS/CFT
Using the gauge/string duality, we derive a set of Langevin equations
describing the dynamics of a relativistic heavy quark moving with constant
average speed through the strongly-coupled N=4 SYM plasma at finite
temperature. We show that the stochasticity arises at the string world-sheet
horizon, and thus is causally disconnected from the black hole horizon in the
space-time metric. This hints at the non-thermal nature of the fluctuations, as
further supported by the fact that the noise term and the drag force in the
Langevin equations do not obey the Einstein relation. We propose a physical
picture for the dynamics of the heavy quark in which dissipation and
fluctuations are interpreted as medium-induced radiation and the associated
quantum-mechanical fluctuations. This picture provides the right parametric
estimates for the drag force and the (longitudinal and transverse) momentum
broadening coefficients.Comment: 25 pages, 4 figure
Calculating the jet-quenching parameter in STU background
In this paper we use the AdS/CFT correspondence to compute the jet-quenching
parameter in a N=2 thermal plasma. We consider the general three-charge black
hole and discuss some special cases. We add a constant electric field to the
background and find the effect of the electric field on the jet-quenching
parameter. Also we include higher derivative terms and obtain the first-order
correction for the jet-quenching parameter.Comment: 17 pages, 3 figures, revised versio
Jet-quenching of the rotating heavy meson in a =4 SYM plasma in presence of a constant electric field
In this paper, we consider a rotating heavy quark-antiquark () pair
in a =4 SYM thermal plasma. We assume that center of
mass moves at the speed and furthermore they rotate around the center of
mass. We use the AdS/CFT correspondence and consider the effect of external
electromagnetic field on the motion of the rotating meson. Then we calculate
the jet-quenching parameter corresponding to the rotating meson in the constant
electric field
STU/QCD Correspondence
In this review article we consider a special case of ,
supergravity called the STU model. We apply the gauge/gravity correspondence to
the STU model to gain insight into properties of the quark-gluon plasma. Given
that the quark-gluon plasma is in reality described by QCD, therefore we call
our study STU/QCD correspondence. First, we investigate the thermodynamics and
hydrodynamics of the STU background. Then we use dual picture of the theory,
which is type IIB string theory, to obtain the drag force and jet-quenching
parameter of an external probe quark.Comment: 56 pages, 20 figures. The paper is review of previous papers
arXiv:0905.1466, arXiv:1005.1368, arXiv:1011.2291 and arXiv:1011.2291.
Published versio