4,529 research outputs found
Transverse Spectra of Radiation Processes in Medium
We develop a formalism for evaluation of the transverse momentum dependence
of cross sections of the radiation processes in medium. The analysis is based
on the light-cone path integral approach to the induced radiation. The results
are applicable in both QED and QCD
The role of finite kinematic bounds in the induced gluon emission from fast quarks in a finite size quark-gluon plasma
We study the influence of finite kinematic boundaries on the induced gluon
radiation from a fast quark in a finite size quark-gluon plasma. The
calculations are carried out for fixed and running coupling constant. We find
that for running coupling constant the kinematic correction to the radiative
energy loss is small for quark energy larger than about 5 GeV. Our results
differ both analytically and numerically from that obtained by the GLV group
[6]. The effect of the kinematic cut-offs is considerably smaller than reported
in [6].Comment: 11 pages, 4 figure
New multidimensional partially integrable generalization of S-integrable N-wave equation
This paper develops a modification of the dressing method based on the
inhomogeneous linear integral equation with integral operator having nonempty
kernel. Method allows one to construct the systems of multidimensional Partial
Differential Equations (PDEs) having the differential polynomial forms in any
dimension n. Associated solution space is not full, although it is parametrized
by a certain number of arbitrary functions of (n-1)-variables. We consider
4-dimensional generalization of the classical (2+1)-dimensional S-integrable
N-wave equation as an example.Comment: 38 page
Collinear Photon Emission from the Quark-Gluon Plasma: The Light-Cone Path Integral Formulation
We give a simple physical derivation of the photon emission rate from the
weakly coupled quark-gluon plasma connected with the collinear processes and . The analysis is based on the light-cone
path integral approach to the induced radiation. Our results agree with that by
Arnold, Moore and Yaffe obtained using the real-time thermal perturbation
theory. It is demonstrated that the solution of the AMY integral equation is
nothing but the time-integrated Green's function of the light-cone path
integral approach written in the momentum representation.Comment: 12 pages, 2 figure
Anomalous mass dependence of radiative quark energy loss in a finite-size quark-gluon plasma
We demonstrate that for a finite-size quark-gluon plasma the induced gluon
radiation from heavy quarks is stronger than that for light quarks when the
gluon formation length becomes comparable with (or exceeds) the size of the
plasma. The effect is due to oscillations of the light-cone wave function for
the in-medium transition. The dead cone model by Dokshitzer and
Kharzeev neglecting quantum finite-size effects is not valid in this regime.
The finite-size effects also enhance the photon emission from heavy quarks.Comment: 8 pages, 3 figure
Quantum Many-Body Dynamics of Dark Solitons in Optical Lattices
We present a fully quantum many-body treatment of dark solitons formed by
ultracold bosonic atoms in one-dimensional optical lattices. Using
time-evolving block decimation to simulate the single-band Bose-Hubbard
Hamiltonian, we consider the quantum dynamics of density and phase engineered
dark solitons as well as the quantum evolution of mean-field dark solitons
injected into the quantum model. The former approach directly models how one
may create quantum entangled dark solitons in experiment. While we have already
presented results regarding the latter approach elsewhere [Phys. Rev. Lett.
{\bf 103}, 140403 (2009)], we expand upon those results in this work. In both
cases, quantum fluctuations cause the dark soliton to fill in and may induce an
inelasticity in soliton-soliton collisions. Comparisons are made to the
Bogoliubov theory which predicts depletion into an anomalous mode that fills in
the soliton. Our many-body treatment allows us to go beyond the Bogoliubov
approximation and calculate explicitly the dynamics of the system's natural
orbitals.Comment: 14 pages, 11 figures -- v3 has only minor changes from v2 -- this is
the print versio
Radiative parton energy loss and jet quenching in high-energy heavy-ion collisions
We study within the light-cone path integral approach [3] the effect of the
induced gluon radiation on high-p_{T} hadrons in high-energy heavy-ion
collisions. The induced gluon spectrum is represented in a new form which is
convenient for numerical simulations. For the first time, computations are
performed with a realistic parametrization of the dipole cross section. The
results are in reasonable agreement with suppression of high-p_{T} hadrons in
Au+Au collisions at \sqrt{s}=200 GeV observed at RHIC.Comment: 12 pages, 3 epsi figures. Typos correcte
Partially integrable systems in multidimensions by a variant of the dressing method. 1
In this paper we construct nonlinear partial differential equations in more
than 3 independent variables, possessing a manifold of analytic solutions with
high, but not full, dimensionality. For this reason we call them ``partially
integrable''. Such a construction is achieved using a suitable modification of
the classical dressing scheme, consisting in assuming that the kernel of the
basic integral operator of the dressing formalism be nontrivial. This new
hypothesis leads to the construction of: 1) a linear system of compatible
spectral problems for the solution of the integral equation in 3
independent variables each (while the usual dressing method generates spectral
problems in 1 or 2 dimensions); 2) a system of nonlinear partial differential
equations in dimensions (), possessing a manifold of analytic
solutions of dimension (), which includes one largely arbitrary relation
among the fields. These nonlinear equations can also contain an arbitrary
forcing.Comment: 21 page
Energy loss in perturbative QCD
We review the properties of energetic parton propagation in hot or cold QCD
matter, as obtained in recent works. Advances in understanding the energy loss
- collisional and radiative - are summarized, with emphasis on the latter: it
features very interesting properties which may help to detect the quark-gluon
plasma produced in heavy ion collisions. We describe two different theoretical
approaches, which lead to the same radiated gluon energy spectrum. The case of
a longitudinally expanding QCD plasma is investigated. The energy lost by a jet
with given opening angle is calculated in view of making predictions for the
suppression (quenching) of hard jet production. Phenomenological implications
for the difference between hot and cold matter are discussed. Numerical
estimates of the loss suggest that it may be significantly enhanced in hot
compared to cold matter.Comment: 49 pages latex file with 11 embedded PS figures. Uses ar.sty
(included), one equation revised. submitted to Annual Review of Nuclear and
Particle Scienc
Medium-induced radiative energy loss; equivalence between the BDMPS and Zakharov formalisms
We extend the BDMPS formalism for calculating radiative energy loss to the
case when the radiated gluon carries a finite fraction of the quark momentum.
Some virtual terms, previously overlooked, are now included. The equivalence
between the formalism of BDMPS and that of B.Zakharov is explicitly
demonstrated.Comment: 23 pages, 7 eps figures; uses amsmat
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