1,503 research outputs found
(Non)-Renormalization of the Chiral Vortical Effect Coefficient
We show using diagramtic arguments that in some (but not all) cases, the
temperature dependent part of the chiral vortical effect coefficient is
independent of the coupling constant. An interpretation of this result in terms
of quantization in the effective 3 dimensional Chern-Simons theory is also
given. In the language of 3D dimensionally reduced theory, the value of the
chiral vortical coefficient is related to the formula . We also show that in the presence of dynamical gauge fields, the CVE
coefficient is not protected from renormalization, even in the large limit.Comment: 11 pages, 3 figures. Version 2 corrects an error and calculates
leading radiative correctio
Real-time correlators in warped AdS/CFT correspondence
We study real-time correlators in the warped AdS/CFT correspondence. We apply
the prescription used in the usual AdS/CFT correspondence and obtain the
retarded Green's functions for the scalar and vector fields in the spacelike
warped and the null warped black hole backgrounds. We find that the retarded
Green's functions and the cross sections are well consistent with the
predictions from dual CFT. Our results not only support strongly the
conjectured warped AdS/CFT correspondence, but also show that the usual
relativistic AdS/CFT prescription of obtaining the real-time correlators remain
effective in more general backgrounds with anisotropic conformal infinity.Comment: 27 page
Universal time-dependent deformations of Schrodinger geometry
We investigate universal time-dependent exact deformations of Schrodinger
geometry. We present 1) scale invariant but non-conformal deformation, 2)
non-conformal but scale invariant deformation, and 3) both scale and conformal
invariant deformation. All these solutions are universal in the sense that we
could embed them in any supergravity constructions of the Schrodinger invariant
geometry. We give a field theory interpretation of our time-dependent
solutions. In particular, we argue that any time-dependent chemical potential
can be treated exactly in our gravity dual approach.Comment: 24 pages, v2: references adde
Probe Branes, Time-dependent Couplings and Thermalization in AdS/CFT
We present holographic descriptions of thermalization in conformal field
theories using probe D-branes in AdS X S space-times. We find that the induced
metrics on Dp-brane worldvolumes which are rotating in an internal sphere
direction have horizons with characteristic Hawking temperatures even if there
is no black hole in the bulk AdS. The AdS/CFT correspondence applied to such
systems indeed reveals thermal properties such as Brownian motions and AC
conductivities in the dual conformal field theories. We also use this framework
to holographically analyze time-dependent systems undergoing a quantum quench,
where parameters in quantum field theories, such as a mass or a coupling
constant, are suddenly changed. We confirm that this leads to thermal behavior
by demonstrating the formation of apparent horizons in the induced metric after
a certain time.Comment: LaTeX, 47 pages, 14 figures; Typos corrected and references added
(v2); minor corrections, references added(v3
Stringy effects in black hole decay
We compute the low energy decay rates of near-extremal three(four) charge
black holes in five(four) dimensional N=4 string theory to sub-leading order in
the large charge approximation. This involves studying stringy corrections to
scattering amplitudes of a scalar field off a black hole. We adapt and use
recently developed techniques to compute such amplitudes as near-horizon
quantities. We then compare this with the corresponding calculation in the
microscopic configuration carrying the same charges as the black hole. We find
perfect agreement between the microscopic and macroscopic calculations; in the
cases we study, the zero energy limit of the scattering cross section is equal
to four times the Wald entropy of the black hole.Comment: 32 page
Holographic Brownian Motion in Magnetic Environments
Using the gauge/gravity correspondence, we study the dynamics of a heavy
quark in two strongly-coupled systems at finite temperature: Super-Yang-Mills
in the presence of a magnetic field and non-commutative Super-Yang-Mills. In
the former, our results agree qualitatively with the expected behavior from
weakly-coupled theories. In the latter, we propose a Langevin equation that
accounts for the effects of non-commutativity and we find new interesting
features. The equation resembles the structure of Brownian motion in the
presence of a magnetic field and implies that the fluctuations along
non-commutative directions are correlated. Moreover, our results show that the
viscosity is smaller than the commutative case and that the diffusion
properties of the quark are unaffected by non-commutativity. Finally, we
compute the random force autocorrelator and verify that the
fluctuation-dissipation theorem holds in the presence of non-commutativity.Comment: 34 pages. v2: typos corrected. v3: title and abstract slightly
modified in order to better reflect the contents of the paper; footnote 3 and
one reference were also added; version accepted for publication in JHE
Lifshitz spacetimes from AdS null and cosmological solutions
We describe solutions of 10-dimensional supergravity comprising null
deformations of with a scalar field, which have
Lifshitz symmetries. The bulk Lifshitz geometry in 3+1-dimensions arises by
dimensional reduction of these solutions. The dual field theory in this case is
a deformation of the N=4 super Yang-Mills theory. We discuss the holographic
2-point function of operators dual to bulk scalars. We further describe
time-dependent (cosmological) solutions which have anisotropic Lifshitz scaling
symmetries. We also discuss deformations of in 11-dimensional
supergravity, which are somewhat similar to the solutions above. In some cases
here, we expect the field theory duals to be deformations of the Chern-Simons
theories on M2-branes stacked at singularities.Comment: Latex, 29pgs, v3. references, minor clarifications (subsection on
Lifshitz geometry seen by scalar probes) added, to appear in JHE
Orbifold equivalence for finite density QCD and effective field theory
In the large N_c limit, some apparently different gauge theories turn out to
be equivalent due to large N_c orbifold equivalence. We use effective field
theory techniques to explore orbifold equivalence, focusing on the specific
case of a recently discovered relation between an SO(2N_c) gauge theory and
QCD. The equivalence to QCD has been argued to hold at finite baryon chemical
potential, \mu_B, so long as one deforms the SO(2N_c) theory by certain
"double-trace" terms. The deformed SO(2N_c) theory can be studied without a
sign problem in the chiral limit, in contrast to SU(N_c) QCD at finite \mu_B.
The purpose of the double-trace deformation in the SO(2N_c) theory is to
prevent baryon number symmetry from breaking spontaneously at finite density,
which is necessary for the equivalence to large N_c QCD to be valid. The
effective field theory analysis presented here clarifies the physical
significance of double-trace deformations, and strongly supports the proposed
equivalence between the deformed SO(2N_c) theory and large N_c QCD at finite
density.Comment: 39 pages, 5 figures, 2 tables. v2: Minor typo fixes and
clarification
Holographic DC conductivities from the open string metric
We study the DC conductivities of various holographic models using the open
string metric (OSM), which is an effective metric geometrizing density and
electromagnetic field effect. We propose a new way to compute the nonlinear
conductivity using OSM. As far as the final conductivity formula is concerned,
it is equivalent to the Karch-O'Bannon's real-action method. However, it yields
a geometrical insight and technical simplifications. Especially, a real-action
condition is interpreted as a regular geometry condition of OSM. As
applications of the OSM method, we study several holographic models on the
quantum Hall effect and strange metal. By comparing a Lifshitz background and
the Light-Cone AdS, we show how an extra parameter can change the temperature
scaling behavior of conductivity. Finally we discuss how OSM can be used to
study other transport coefficients, such as diffusion constant, and effective
temperature induced by the effective world volume horizon.Comment: 33 page
Hemangiopericytoma of the Greater Omentum
A 41-year-old Chinese woman was admitted to our hospital with epigastric pain. Computed tomography detected a heterogeneous enhancement tumor fed by the left gastroepiploic artery in the left lower quadrant and cholelithiasis. Excision of the tumor in the greater omentum and cholecystectomy were performed laparoscopically. Histological findings confirmed a diagnosis of hemangiopericytoma with low-grade malignancy. To our knowledge, hemangiopericytoma of the greater omentum is very rare, and only 12 cases were reported in English literature. We report a case of hemangiopericytoma arising in the greater omentum and review the literature
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