869 research outputs found
Stability of AdS black strings
We review the recent developements in the stability problem and phase diagram
for asymptotically locally black strings. First, we quickly review the
case of locally flat black string before turning to the case of locally
spacetimes.Comment: 4 pages. Talk included in the 7th Friedmann Seminar, Joao Pessoa -
Brazi
The Final State of Black Strings and p-Branes, and the Gregory-Laflamme Instability
It is shown that the usual entropy argument for the Gregory-Laflamme (GL)
instability for appropriate black strings and -branes gives
surprising agreement up to a few percent. This may provide a strong support to
the GL's horizon fragmentation, which would produce the array of
higher-dimensional Schwarzschild-type's black holes finally. On the other hand,
another estimator for the size of the black hole end-state relative to the
compact dimension indicates a second order (i.e., smooth) phase transition for
some appropriate compactifications and total dimension of spacetime
wherein the entropy argument is not appropriate. In this case,
Horowitz-Maeda-type's non-uniform black strings or -branes can be the final
state of the GL instability.Comment: More emphasis on a second order phase transition. The computation
result is unchange
Entropy and Temperature of Black 3-Branes
We consider slightly non-extremal black 3-branes of type IIB supergravity and
show that their Bekenstein-Hawking entropy agrees, up to a mysterious factor,
with an entropy derived by counting non-BPS excitations of the Dirichlet
3-brane. These excitations are described in terms of the statistical mechanics
of a 3+1 dimensional gas of massless open string states. This is essentially
the classic problem of blackbody radiation. The blackbody temperature is
related to the temperature of the Hawking radiation. We also construct a
solution of type IIB supergravity describing a 3-brane with a finite density of
longitudinal momentum. For extremal momentum-carrying 3-branes the horizon area
vanishes. This is in agreement with the fact that the BPS entropy of the
momentum-carrying Dirichlet 3-branes is not an extensive quantity.Comment: 10 pages, LaTeX, minor revisions. v3: version that appeared in PR
On equilibration and coarsening in the quantum O(N) model at infinite
The quantum O(N) model in the infinite limit is a paradigm for
symmetry-breaking. Qualitatively, its phase diagram is an excellent guide to
the equilibrium physics for more realistic values of in varying spatial
dimensions (). Here we investigate the physics of this model out of
equilibrium, specifically its response to global quenches starting in the
disordered phase. If the model were to exhibit equilibration, the late time
state could be inferred from the finite temperature phase diagram. In the
infinite limit, we show that not only does the model not lead to
equilibration on account of an infinite number of conserved quantities, it also
does \emph{not} relax to a generalized Gibbs ensemble consistent with these
conserved quantities. Nevertheless, we \emph{still} find that the late time
states following quenches bear strong signatures of the equilibrium phase
diagram. Notably, we find that the model exhibits coarsening to a
non-equilibrium critical state only in dimensions , that is, if the
equilibrium phase diagram contains an ordered phase at non-zero temperatures.Comment: 11 pages, 9 figure
Continuous distributions of D3-branes and gauged supergravity
States on the Coulomb branch of N=4 super-Yang-Mills theory are studied from
the point of view of gauged supergravity in five dimensions. These
supersymmetric solutions provide examples of consistent truncation from type
IIB supergravity in ten dimensions. A mass gap for states created by local
operators and perfect screening for external quarks arise in the supergravity
approximation. We offer an interpretation of these surprising features in terms
of ensembles of brane distributions.Comment: 19 pages, two figures, latex. v2: reference added, small corrections.
v3: corrected unbounded spectrum erro
Renormalization Group Flows from Holography--Supersymmetry and a c-Theorem
We obtain first order equations that determine a supersymmetric kink solution
in five-dimensional N=8 gauged supergravity. The kink interpolates between an
exterior anti-de Sitter region with maximal supersymmetry and an interior
anti-de Sitter region with one quarter of the maximal supersymmetry. One eighth
of supersymmetry is preserved by the kink as a whole. We interpret it as
describing the renormalization group flow in N=4 super-Yang-Mills theory broken
to an N=1 theory by the addition of a mass term for one of the three adjoint
chiral superfields. A detailed correspondence is obtained between fields of
bulk supergravity in the interior anti-de Sitter region and composite operators
of the infrared field theory. We also point out that the truncation used to
find the reduced symmetry critical point can be extended to obtain a new N=4
gauged supergravity theory holographically dual to a sector of N=2 gauge
theories based on quiver diagrams.
We consider more general kink geometries and construct a c-function that is
positive and monotonic if a weak energy condition holds in the bulk gravity
theory. For even-dimensional boundaries, the c-function coincides with the
trace anomaly coefficients of the holographically related field theory in
limits where conformal invariance is recovered.Comment: 56 pages, three figures, harvmac. v2: improved referencing, corrected
discussion of energy conditions. v3: one more reference fixe
Critical Behavior in the Rotating D-branes
The low energy excitation of the rotating D3-branes is thermodynamically
stable up to a critical angular momentum density. This indicates that there is
a corresponding phase transition of the =4 large super Yang-Mills
theory at finite temperature. On the side of supergravity, we investigate the
phase transition in the grand canonical ensemble and canonical ensemble. Some
critical exponents of thermodynamic quantities are calculated. They obey the
static scaling laws. Using the scaling laws related to the correlation length,
we get the critical exponents of the correlation function of gauge field. The
thermodynamic stability of low energy excitations of the rotating M5-branes and
rotating M2-branes is also studied and similar critical behavior is observed.
We find that the critical point is shifted in the different ensembles and there
is no critical point in the canonical ensemble for the rotating M2-branes. We
also discuss the Hawking-Page transition for these rotating branes. In the
grand canonical ensemble, the Hawking-Page transition does not occur. In the
canonical ensemble, however, the Hawking-Page transition may appear for the
rotating D3- and M5-branes, but not for the rotating M2-branes.Comment: Revtex, 17 pages, minor changes, the discussion on the Hawking-Page
transition and references adde
On non-uniform smeared black branes
We investigate charged dilatonic black -branes smeared on a transverse
circle. The system can be reduced to neutral vacuum black branes, and we
perform static perturbations for the reduced system to construct non-uniform
solutions. At each order a single master equation is derived, and the
Gregory-Laflamme critical wavelength is determined. Based on the non-uniform
solutions, we discuss thermodynamic properties of this system and argue that in
a microcanonical ensemble the non-uniform smeared branes are entropically
disfavored even near the extremality, if the spacetime dimension is , which is the critical dimension for the vacuum case. However, the critical
dimension is not universal. In a canonical ensemble the vacuum non-uniform
black branes are thermodynamically favorable at , whereas the
non-uniform smeared branes are favorable at near the extremality.Comment: 24 pages, 2 figures; v2: typos corrected, submitted to
Class.Quant.Gra
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