76 research outputs found
Kinetic equation for gluons at the early stage
We derive the kinetic equation for pure gluon QCD plasma in a general way,
applying the background field method. We show that the quantum kinetic equation
contains a term as in the classical case, that describes a color charge
precession of partons moving in the gauge field. We emphasize that this new
term is necessary for the gauge covariance of the resulting equation.Comment: 6 pages, no figure, to appear in the proceedings of the 6th
international conference on strange quarks in matter, Frankfurt, Germany,
25-29 september 200
Open and Hidden Charm Production in Heavy Ion Collisions at Ultrarelativistic Energies
We consider the production of the open charm and J/psi mesons in heavy ion
collisions at BNL RHIC. We discuss several recently developed pictures for
J/psi production and argue that a measurement at RHIC energies is crucial for
disentangling these different descriptions.Comment: 19 pages, Latex, 5 PS-figures. v3: Fig.6 is adde
The High E_T Drop of J/psi to Drell-Yan Ratio from the Statistical c anti-c Coalescence Model
The dependence of the J/psi yield on the transverse energy E_T in heavy ion
collisions is considered within the statistical c anti-c coalescence model. The
model fits the NA50 data for Pb+Pb collisions at the CERN SPS even in the
high-E_T region (E_T > 100 GeV). Here E_T-fluctuations and E_T-losses in the
dimuon event sample naturally create the celebrated drop in the J/psi to
Drell-Yan ratio.Comment: 14 pages, REVTeX, 1 PS-figure. v2: References are corrected and
update
In-medium relativistic kinetic theory and nucleon-meson systems
Within the model of coupled nucleon-meson systems, a
generalized relativistic Lenard--Balescu--equation is presented resulting from
a relativistic random phase approximation (RRPA). This provides a systematic
derivation of relativistic transport equations in the frame of nonequilibrium
Green's function technique including medium effects as well as flucuation
effects. It contains all possible processes due to one meson exchange and
special attention is kept to the off--shell character of the particles. As a
new feature of many particle effects, processes are possible which can be
interpreted as particle creation and annihilation due to in-medium one meson
exchange. In-medium cross sections are obtained from the generalized derivation
of collision integrals, which possess complete crossing symmetries.Comment: See nucl-th/9310032 for revised version which the authors
incompetently resubmitted rather than correctly replacing thi
Thermal photons as a measure for the rapidity dependence of the temperature
The rapidity distribution of thermal photons produced in Pb+Pb collisions at
CERN-SPS energies is calculated within scaling and three-fluid hydrodynamics.
It is shown that these scenarios lead to very different rapidity spectra. A
measurement of the rapidity dependence of photon radiation can give cleaner
insight into the reaction dynamics than pion spectra, especially into the
rapidity dependence of the temperature.Comment: 3 Figure
Indications of suppression of excited ÎĽ states in Pb-Pb collisions at âsNN = 2.76TeV
This is the pre-print version of the Published Article which can be accessed from the link below.A comparison of the relative yields of ÎĽ resonances in the Îź+Îź- decay channel in Pb-Pb and pp collisions at a center-of-mass energy per nucleon pair of 2.76 TeV is performed with data collected with the CMS detector at the LHC. Using muons of transverse momentum above 4ââGeV/c and pseudorapidity below 2.4, the double ratio of the ÎĽ(2S) and ÎĽ(3S) excited states to the ÎĽ(1S) ground state in Pb-Pb and pp collisions, [ÎĽ(2S+3S)/ÎĽ(1S)]Pb-Pb/[ÎĽ(2S+3S)/ÎĽ(1S)]pp, is found to be 0.31-0.15+0.19(stat)Âą0.03(syst). The probability to obtain the measured value, or lower, if the true double ratio is unity, is calculated to be less than 1%
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