265 research outputs found
Buerger's disease manifesting nodular erythema with livedo reticularis
ArticleINTERNAL MEDICINE. 46(21):1815-1819(2007)journal articl
The Chiral Model of Sakai-Sugimoto at Finite Baryon Density
In the context of holographic QCD we analyze Sakai-Sugimoto's chiral model at
finite baryon density and zero temperature. The baryon number density is
introduced through compact D4 wrapping S^4 at the tip of D8-\bar{D8}. Each
baryon acts as a chiral point-like source distributed uniformly over R^3, and
leads a non-vanishing U(1)_V potential on the brane. For fixed baryon charge
density n_B we analyze the bulk energy density and pressure using the canonical
formalism. The baryonic matter with point like sources is always in the
spontaneously broken phase of chiral symmetry, whatever the density. The
point-like nature of the sources and large N_c cause the matter to be repulsive
as all baryon interactions are omega mediated. Through the induced DBI action
on D8-\bar{D8}, we study the effects of the fixed baryon charge density n_B on
the pion and vector meson masses and couplings. Issues related to vector
dominance in matter in the context of holographic QCD are also discussed.Comment: V3: 39 pages, 16 figures, minor corrections, version to appear in
JHEP. V2: references added, typos correcte
A Dual Geometry of the Hadron in Dense Matter
We identify the dual geometry of the hadron phase of dense nuclear matter and
investigate the confinement/deconfinement phase transition. We suggest that the
low temperature phase of the RN black hole with the full backreaction of the
bulk gauge field is described by the zero mass limit of the RN black hole with
hard wall. We calculated the density dependence of critical temperature and
found that the phase diagram closes. We also study the density dependence of
the rho meson mass.Comment: 16 pages, 4 figures, typos corrected, references adde
Holographic Thermodynamics at Finite Baryon Density: Some Exact Results
We use the AdS/CFT correspondence to study the thermodynamics of massive N=2
supersymmetric hypermultiplets coupled to N=4 supersymmetric SU(Nc) Yang-Mills
theory in the limits of large Nc and large 't Hooft coupling. In particular, we
study the theory at finite baryon number density. At zero temperature, we
present an exact expression for the hypermultiplets' leading-order contribution
to the free energy, and in the supergravity description we clarify which
D-brane configuration is appropriate for any given value of the chemical
potential. We find a second-order phase transition when the chemical potential
equals the mass. At finite temperature, we present an exact expression for the
hypermultiplets' leading-order contribution to the free energy at zero mass.Comment: 21 pages, 1 figure; v2 corrected typos, added comments to sections
2.2 and 2.
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
Bulk Filling Branes and the Baryon Density in AdS/QCD with gravity back-reaction
We consider the gravity back reaction on the metric due to the baryon density
in effective ads/qcd model by reconsidering the role of the charged AdS black
hole. Previously it has been known that the U(1) charge is dual to the
R-charge. Here we point out that if we consider the case where is
completely filled with flavor branes, the gravity back reaction produces
charged AdS black hole where the effect of charge on the metric is proportional
to . As a consequence, phase diagram changes qualitatively if we allow
finite: it closes at the finite density unlike the probe brane
embedding approach.
Another issue we discuss here is the question whether there is any chemical
potential dependence in the confining phase. We consider this problem in the
hard wall model with baryon charge. We conclude that there is a non-trivial
dependence on the chemical potential in this case also.Comment: 17 pages 3x2 figures, v2: references added;v3 published version,
title change and reference adde
Cold Nuclear Matter In Holographic QCD
We study the Sakai-Sugimoto model of holographic QCD at zero temperature and
finite chemical potential. We find that as the baryon chemical potential is
increased above a critical value, there is a phase transition to a nuclear
matter phase characterized by a condensate of instantons on the probe D-branes
in the string theory dual. As a result of electrostatic interactions between
the instantons, this condensate expands towards the UV when the chemical
potential is increased, giving a holographic version of the expansion of the
Fermi surface. We argue based on properties of instantons that the nuclear
matter phase is necessarily inhomogeneous to arbitrarily high density. This
suggests an explanation of the "chiral density wave" instability of the quark
Fermi surface in large N_c QCD at asymptotically large chemical potential. We
study properties of the nuclear matter phase as a function of chemical
potential beyond the transition and argue in particular that the model can be
used to make a semi-quantitative prediction of the binding energy per nucleon
for nuclear matter in ordinary QCD.Comment: 31 pages, LaTeX, 1 figure, v2: some formulae corrected, qualitative
results unchange
Criticality, Scaling and Chiral Symmetry Breaking in External Magnetic Field
We consider a D7-brane probe of in the presence of pure
gauge -field. The dual gauge theory is flavored Yang-Mills theory in
external magnetic field. We explore the dependence of the fermionic condensate
on the bare quark mass and study the discrete self-similar behavior of
the theory near the origin of the parametric space. We calculate the critical
exponents of the bare quark mass and the fermionic condensate. A study of the
meson spectrum supports the expectation based on thermodynamic considerations
that at zero bare quark mass the stable phase of the theory is a chiral
symmetry breaking one. Our study reveals the self-similar structure of the
spectrum near the critical phase of the theory, characterized by zero fermionic
condensate and we calculate the corresponding critical exponent of the meson
spectrum.Comment: 29 pages, 9 figures. Accepted in JHEP. Updated to mach the published
version. One figure added, some definitions improve
Notes on Properties of Holographic Matter
Probe branes with finite worldvolume electric flux in the background created
by a stack of Dp branes describe holographically strongly interacting
fundamental matter at finite density. We identify two quantities whose leading
low temperature behavior is independent of the dimensionality of the probe
branes: specific heat and DC conductivity. This behavior can be inferred from
the dynamics of the fundamental strings which provide a good description of the
probe branes in the regime of low temperatures and finite densities. We also
comment on the speed of sound on the branes and the temperature dependence of
DC conductivity at vanishing charge density.Comment: 18 pages, 2 figures; v2: corrected error in Section 6, conclusions
unchanged; v3: improved figures and added clarifying comment
Thermodynamic Properties of Holographic Multiquark and the Multiquark Star
We study thermodynamic properties of the multiquark nuclear matter. The
dependence of the equation of state on the colour charges is explored both
analytically and numerically in the limits where the baryon density is small
and large at fixed temperature between the gluon deconfinement and chiral
symmetry restoration. The gravitational stability of the hypothetical
multiquark stars are discussed using the Tolman-Oppenheimer-Volkoff equation.
Since the equations of state of the multiquarks can be well approximated by
different power laws for small and large density, the content of the multiquark
stars has the core and crust structure. We found that most of the mass of the
star comes from the crust region where the density is relatively small. The
mass limit of the multiquark star is determined as well as its relation to the
star radius. For typical energy density scale of ,
the converging mass and radius of the hypothetical multiquark star in the limit
of large central density are approximately solar mass and 15-27 km.
The adiabatic index and sound speed distributions of the multiquark matter in
the star are also calculated and discussed. The sound speed never exceeds the
speed of light and the multiquark matters are thus compressible even at high
density and pressure.Comment: 27 pages, 17 figures, 1 table, JHEP versio
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