1,163 research outputs found
Can the correlated stability conjecture be saved?
Correlated stability conjecture (CSC) proposed by Gubser and Mitra [1,2]
linked the thermodynamic and classical (in)stabilities of black branes. In [3]
it was shown that the thermodynamic instabilities, specifically the negative
specific heat, indeed result in the instabilities in the hydrodynamic spectrum
of holographically dual plasma excitations. Counter-examples of CSC were
presented in the context of black branes with scalar hair undergoing a
second-order phase transition [4,5]. The latter translationary invariant
horizons have scalar hair, raising the question whether the asymptotic
parameters of the scalar hair can be appropriately interpreted as additional
charges leading to a generalization of the thermodynamic stability criterion.
In this paper we show that the generalization of the thermodynamic stability
criterion of this type can not save CSC. We further present a simple
statistical model which makes it clear that thermodynamic and dynamical
(in)stabilities generically are not correlated.Comment: 9 pages, 2 figures; v2: JHEP versio
Holographic bulk viscosity: GPR vs EO
Recently Eling and Oz (EO) proposed a formula for the holographic bulk
viscosity, in arXiv:1103.1657, derived from the null horizon focusing equation.
This formula seems different from that obtained earlier by Gubser, Pufu and
Rocha (GPR) in arXiv:0806.0407 calculated from the IR limit of the two-point
function of the trace of the stress tensor. The two were shown to agree only
for some simple scaling cases. We point out that the two formulae agree in two
non-trivial holographic theories describing RG flows. The first is the strongly
coupled N=2* gauge theory plasma. The second is the semi-phenomenological model
of Improved Holographic QCD.Comment: 21 pages, 2 figure
The Tachyon does Matter
We review the concept of S-branes introduced by Gutperle and Strominger
hep-th/0202210. Using the effective spacetime description of the rolling
tachyon worldsheets discussed by Sen, we analyze the possibility that the
gravitational backreaction of tachyon matter is important in the time-dependent
process. We show that this is indeed the case in the example of the S0-brane in
4-dimensional Einstein-Maxwell theory. This talk is based on hep-th/0207235.Comment: 8 pages, Talk given at 35th Symposium Ahrenshoop, Contribution to the
Proceeding
Cascading gauge theory on dS_4 and String Theory Landscape
Placing anti-D3 branes at the tip of the conifold in Klebanov-Strassler
geometry provides a generic way of constructing meta-stable de Sitter (dS)
vacua in String Theory. A local geometry of such vacua exhibit gravitational
solutions with a D3 charge measured at the tip opposite to the asymptotic
charge. We discuss a restrictive set of such geometries, where anti-D3 branes
are smeared at the tip. Such geometries represent holographic dual of cascading
gauge theory in dS4 with or without chiral symmetry breaking. We find that in
the phase with unbroken chiral symmetry the D3 charge at the tip is always
positive. Furthermore, this charge is zero in the phase with spontaneously
broken chiral symmetry. We show that the effective potential of the chirally
symmetric phase is lower than that in the symmetry broken phase, i.e, there is
no spontaneous chiral symmetry breaking for cascading gauge theory in dS4. The
positivity of the D3 brane charge in smooth de-Sitter deformed conifold
geometries with fluxes presents difficulties in uplifting AdS vacua to dS ones
in String Theory via smeared anti-D3 branes.Comment: 47 pages, 6 figures. v2: published version. arXiv admin note:
substantial text overlap with arXiv:1108.607
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
Transport coefficients, membrane couplings and universality at extremality
We present an efficient method for computing the zero frequency limit of
transport coefficients in strongly coupled field theories described
holographically by higher derivative gravity theories. Hydrodynamic parameters
such as shear viscosity and conductivity can be obtained by computing residues
of poles of the off-shell lagrangian density. We clarify in which sense these
coefficients can be thought of as effective couplings at the horizon, and
present analytic, Wald-like formulae for the shear viscosity and conductivity
in a large class of general higher derivative lagrangians. We show how to apply
our methods to systems at zero temperature but finite chemical potential. Our
results imply that such theories satisfy universally in the
Einstein-Maxwell sector. Likewise, the zero frequency limit of the real part of
the conductivity for such systems is shown to be universally zero, and we
conjecture that higher derivative corrections in this sector do not modify this
result to all orders in perturbation theory.Comment: 29 pages, v2: Small text changes for clarity, typos correcte
On effective action of string theory flux compactifications
We discuss four dimensional effective actions of string theory flux
compactifications. These effective actions describe four dimensional gravity
coupled to overall Kahler modulus of the compactification manifold. We
demonstrate the agreement between ten dimensional equations of motion of
supergravity with localized branes, and equations of motion derived from the
effective action. The agreement is lost however if one evaluates the full
effective action on the equations of motion for a subset of the supergravity
modes, provided these modes depend on-shell on the Kahler modulus.Comment: 25 pages; v2: refs adde
Holographic dual of the Eguchi-Kawai mechanism
archiveprefix: arXiv primaryclass: hep-th reportnumber: NORDITA-2014-40, UUITP-03-14, QMUL-PH-14-08 slaccitation: %%CITATION = ARXIV:1404.0225;%%archiveprefix: arXiv primaryclass: hep-th reportnumber: NORDITA-2014-40, UUITP-03-14, QMUL-PH-14-08 slaccitation: %%CITATION = ARXIV:1404.0225;%%archiveprefix: arXiv primaryclass: hep-th reportnumber: NORDITA-2014-40, UUITP-03-14, QMUL-PH-14-08 slaccitation: %%CITATION = ARXIV:1404.0225;%%The work of K.Z. was supported by
the ERC advanced grant No 341222, by the Marie Curie network GATIS of the European
Unionâs FP7 Programme under REA Grant Agreement No 317089, and by the Swedish
Research Council (VR) grant 2013-4329. DY acknowledges NORDITA where this work
was begun, during his time as a NORDITA fellow
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