6,495 research outputs found
Nuclear suppression of meson yields with large at the RHIC and the LHC
We calculate meson transverse momentum spectra in p+p collisions as
well as their nuclear suppressions in central A+A collisions both at the RHIC
and the LHC in LO and NLO with the QCD-improved parton model. We have included
the parton energy loss effect in hot/dense QCD medium with the effectively
medium-modified fragmentation functions in the higher-twist approach of
jet quenching. The nuclear modification factors of meson in central
Au+Au collisions at the RHIC and central Pb+Pb collisions at the LHC are
provided, and a nice agreement of our numerical results at NLO with the ALICE
measurement is observed. Predictions of yield ratios of neutral mesons such as
, and at large in relativistic
heavy-ion collisions are also presented for the first time.Comment: 7 pages, 8 figure
Entropy/Area spectra of the charged black hole from quasinormal modes
With the new physical interpretation of quasinormal modes proposed by
Maggiore, the quantum area spectra of black holes have been investigated
recently. Adopting the modified Hod's treatment, results show that the area
spectra for black holes are equally spaced and the spacings are in a unified
form, , in Einstein gravity. On the other hand,
following Kunstatter's method, the studies show that the area spectrum for a
nonrotating black hole with no charge is equidistant. And for a rotating (or
charged) black hole, it is also equidistant and independent of the angular
momentum (or charge ) when the black hole is far from the extremal case.
In this paper, we mainly deal with the area spectrum of the stringy charged
Garfinkle-Horowitz-Strominger black hole, originating from effective action
that emerges in the low-energy string theory. We find that both methods give
the same results-that the area spectrum is equally spaced and does not depend
on the charge . Our study may provide new insights into understanding the
area spectrum and entropy spectrum for stringy black holes.Comment: 13 pages, no figure
Warped Brane worlds in Critical Gravity
We investigate the brane models in arbitrary dimensional critical gravity
presented in [Phys. Rev. Lett. 106, 181302 (2011)]. For the model of the thin
branes with codimension one, the Gibbons-Hawking surface term and the junction
conditions are derived, with which the analytical solutions for the flat, AdS,
and dS branes are obtained at the critical point of the critical gravity. It is
found that all these branes are embedded in an AdS spacetime, but, in
general, the effective cosmological constant of the AdS
spacetime is not equal to the naked one in the critical gravity,
which can be positive, zero, and negative. Another interesting result is that
the brane tension can also be positive, zero, or negative, depending on the
symmetry of the thin brane and the values of the parameters of the theory,
which is very different from the case in general relativity. It is shown that
the mass hierarchy problem can be solved in the braneworld model in the
higher-derivative critical gravity. We also study the thick brane model and
find analytical and numerical solutions of the flat, AdS, and dS branes. It is
find that some branes will have inner structure when some parameters of the
theory are larger than their critical values, which may result in resonant KK
modes for some bulk matter fields. The flat branes with positive energy density
and AdS branes with negative energy density are embedded in an -dimensional
AdS spacetime, while the dS branes with positive energy density are embedded in
an -dimensional Minkowski one.Comment: 14 pages, 7 figures, updated version, accepted by EPJ
Time-Dependent Scalar Fields in Modified Gravities in a Stationary Spacetime
Most no-hair theorems involve the assumption that the scalar field is
independent of time. Recently in [Phys. Rev. D90 (2014) 041501(R)] the
existence of time-dependent scalar hair outside a stationary black hole in
general relativity was ruled out. We generalize this work to modified gravities
and non-minimally coupled scalar field with an additional assumption that the
spacetime is axisymmetric. It is shown that in higher-order gravity such as
metric gravity the time-dependent scalar hair doesn't exist. While in
Palatini gravity and non-minimally coupled case the time-dependent
scalar hair may exist.Comment: 6 pages, no figure
On q-deformed infinite-dimensional n-algebra
The -deformation of the infinite-dimensional -algebra is investigated.
Based on the structure of the -deformed Virasoro-Witt algebra, we derive a
nontrivial -deformed Virasoro-Witt -algebra which is nothing but a
sh--Lie algebra. Furthermore in terms of the pseud-differential operators on
the quantum plane, we construct the (co)sine -algebra and the -deformed
-algebra. We prove that they are the sh--Lie algebras for
the case of even . An explicit physical realization of the (co)sine
-algebra is given.Comment: 22 page
Probing Transverse Momentum Broadening via Dihadron and Hadron-jet Angular Correlations in Relativistic Heavy-ion Collisions
Dijet, dihadron, hadron-jet angular correlations have been reckoned as
important probes of the transverse momentum broadening effects in relativistic
nuclear collisions. When a pair of high-energy jets created in hard collisions
traverse the quark-gluon plasma produced in heavy-ion collisions, they become
de-correlated due to the vacuum soft gluon radiation associated with the
Sudakov logarithms and the medium-induced transverse momentum broadening. For
the first time, we employ the systematical resummation formalism and establish
a baseline calculation to describe the dihadron and hadron-jet angular
correlation data in and peripheral collisions where the medium effect
is negligible. We demonstrate that the medium-induced broadening and the so-called jet quenching parameter can be
extracted from the angular de-correlations observed in collisions. A
global analysis of dihadron and hadron-jet angular correlation data
renders the best fit for a
quark jet at RHIC top energy. Further experimental and theoretical efforts
along the direction of this work shall significantly advance the quantitative
understanding of transverse momentum broadening and help us acquire
unprecedented knowledge of jet quenching parameter in relativistic heavy-ion
collisions.Comment: 6 pages, 3 figure
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