5,223 research outputs found
Quasi-normal modes of holographic system with Weyl correction and momentum dissipation
We study the charge response in complex frequency plane and the quasi-normal
modes (QNMs) of the boundary quantum field theory with momentum dissipation
dual to a probe generalized Maxwell system with Weyl correction. When the
strength of the momentum dissipation is small, the pole
structure of the conductivity is similar to the case without the momentum
dissipation. The qualitative correspondence between the poles of the real part
of the conductivity of the original theory and the ones of its electromagnetic
(EM) dual theory approximately holds when with
being the Weyl coupling parameter. While the strong momentum
dissipation alters the pole structure such that most of the poles locate at the
purely imaginary axis. At this moment, the correspondence between the poles of
the original theory and its EM dual one is violated when . In addition, for the dominant pole, the EM duality almost holds when
for all except for a small region of
.Comment: 18 pages, 9 figure
Holographic superconductivity from higher derivative theory
We construct a derivative holographic superconductor model in the
-dimensional bulk spacetimes, in which the normal state describes a quantum
critical (QC) phase. The phase diagram and the
condensation as the function of temperature are worked out numerically. We
observe that with the decrease of the coupling parameter , the
critical temperature decreases and the formation of charged scalar
hair becomes harder. We also calculate the optical conductivity. An appealing
characteristic is a wider extension of the superconducting energy gap,
comparing with that of derivative theory. It is expected that this
phenomena can be observed in the real materials of high temperature
superconductor. Also the Homes' law in our present models with and
derivative corrections is explored. We find that in certain range of parameters
and , the experimentally measured value of the universal
constant in Homes' law can be obtained.Comment: 16 pages, 5 figure
Holographic Butterfly Effect at Quantum Critical Points
When the Lyapunov exponent in a quantum chaotic system saturates
the bound , it is proposed that this system has a
holographic dual described by a gravity theory. In particular, the butterfly
effect as a prominent phenomenon of chaos can ubiquitously exist in a black
hole system characterized by a shockwave solution near the horizon. In this
paper we propose that the butterfly velocity can be used to diagnose quantum
phase transition (QPT) in holographic theories. We provide evidences for this
proposal with an anisotropic holographic model exhibiting metal-insulator
transitions (MIT), in which the derivatives of the butterfly velocity with
respect to system parameters characterizes quantum critical points (QCP) with
local extremes in zero temperature limit. We also point out that this proposal
can be tested by experiments in the light of recent progress on the measurement
of out-of-time-order correlation function (OTOC).Comment: 7 figures, 15 page
Comparing a few distributions of transverse momenta in high energy collisions
Transverse momentum spectra of particles produced in high energy collisions
are very important due to their relations to the excitation degree of
interacting system. To describe the transverse momentum spectra, one can use
more than one probability density functions of transverse momenta, which are
simply called the functions or distributions of transverse momenta in some
cases. In this paper, a few distributions of transverse momenta in high energy
collisions are compared with each other in terms of plots to show some
quantitative differences. Meanwhile, in the framework of Tsallis statistics,
the distributions of momentum components, transverse momenta, rapidities, and
pasudorapidities are obtained according to the analytical and Monte Carlo
methods. These analyses are useful to understand carefully different
distributions in high energy collisions.Comment: 11 pages, 7 figures. Results in Physics, Accepte
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