3,610 research outputs found
Complexity and phase transitions in a holographic QCD model
Applying the "Complexity=Action" conjecture, we study the holographic
complexity close to crossover/phase transition in a holographic QCD model
proposed by Gubser et al. This model can realize three types of phase
transition, crossover or first and second order, depending on the parameters of
the dilaton potential. The re-scaled late-time growth rate of holographic
complexity density for the three cases is calculated. Our results show that it
experiences a fast drop/jump close to the critical point while approaching
constants far beyond the critical temperature. Moreover, close to the critical
temperature, it shows a behavior characterizing the type of the transition.
These features suggest that the growth rate of the holographic complexity may
be used as a good parameter to characterize the phase transition. The Lloyd's
bound is always satisfied for the cases we considered but only saturated for
the conformal case.Comment: v1: 14 pages, 2 figures; v2: refs added, minor modifications. arXiv
admin note: substantial text overlap with arXiv:1608.03072; v3: More details
on the Lloyd's bound, matching the published versio
Holographic entanglement entropy close to crossover/phase transition in strongly coupled systems
We investigate the behavior of entanglement entropy in the holographic QCD
model proposed by Gubser et al. By choosing suitable parameters of the scalar
self-interaction potential, this model can exhibit various types of phase
structures: crossover, first order and second order phase transitions. We use
entanglement entropy to probe the crossover/phase transition, and find that it
drops quickly/suddenly when the temperature approaches the critical point which
can be seen as a signal of confinement. Moreover, the critical behavior of the
entanglement entropy suggests that we may use it to characterize the
corresponding phase structures.Comment: v1:19 pages, 5 figures; v2: refs added; v3: 20 pages,
high-temperature behaviors of holographic entanglement entropy are given,
accecpted for publication by NP
Holographic Thermalization in Charged Dilaton Anti-de Sitter Spacetime
We study holographic thermalization in spacetimes with a chemical potential
and a non-trivial dilaton field. Three non-local observables are used to probe
the whole process and investigate the effect of the ratio of the chemical
potential over temperature and the dilaton-Maxwell coupling constant
. It is found that the saturation time is not always a monotonically
increasing function of , the situation depends on . When , larger yields longer saturation time, while for
, the situation becomes more complex. More interesting, we found that
although indeed has influence on the whole thermalization process, it
nearly does not affect the saturation time, which indicates the universality of
the saturation time for the dual one-parameter field theories.Comment: 22 pages, 5 figure
Charged Scalar Perturbations around Garfinkle-Horowitz-Strominger Black Holes
We examine the stability of the Garfinkle-Horowitz-Strominger (GHS) black
hole under charged scalar perturbations. We find that different from the
neutral scalar field perturbations, only two numerical methods, such as the
continued fraction method and the asymptotic iteration method, can keep high
efficiency and accuracy requirements in the frequency domain computations. The
comparisons of the efficiency between these two methods have also been done.
Employing the appropriate numerical method, we show that the GHS black hole is
always stable against charged scalar perturbations. This is different from the
result obtained in the de Sitter and Anti-de Sitter black holes. Furthermore we
argue that in the GHS black hole background there is no amplification of the
incident charged scalar wave to cause the superradiance, so that the
superradiant instability cannot exist in this spacetime.Comment: 24 pages, 5 figure
SL(2,C) gravity on noncommutative space with Poisson structure
The Einstein's gravity theory can be formulated as an SL(2,C) gauge theory in
terms of spinor notations. In this paper, we consider a noncommutative space
with the Poisson structure and construct an SL(2,C) formulation of gravity on
such a space. Using the covariant coordinate technique, we build a gauge
invariant action in which, according to the Seiberg-Witten map, the physical
degrees of freedom are expressed in terms of their commutative counterparts up
to the first order in noncommutative parameters.Comment: 12 pages, no figures; v2: 13 pages, clarifications and references
added; v3: clarifications added; v4: more clarifications and references
added, final version to appear in Phys. Rev.
Superradiant instability of Kerr-de Sitter black holes in scalar-tensor theory
We investigate in detail the mechanism of superradiance to render the
instability of Kerr-de Sitter black holes in scalar-tensor gravity. Our results
provide more clues to examine the scalar-tensor gravity in the astrophysical
black holes in the universe with cosmological constant. We also discuss the
spontaneous scalarization in the de Sitter background and find that this
instability can also happen in the spherical de Sitter configuration in a
special style.Comment: (v2)21 pages, 21 figures; Sec. V revised; This version has been
accepted for publication by JHE
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