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Register a new userCharmonium dissociation and recombination at RHIC and LHC
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Charmonium production at heavy-ion colliders is considered within the comovers interaction model. The formalism is extended by including possible secondary J/psi production through recombination and an estimate of recombination effects is made with no free parameters involved. The comovers interaction model also includes a comprehensive treatment of initial-state nuclear effects, which are discussed in the context of such high energies. With these tools, the model properly describes the centrality and the rapidity dependence of experimental data at RHIC energy, $sqrt{s}$ = 200 GeV, for both Au+Au and Cu+Cu collisions. Predictions for LHC, $sqrt{s}$ = 5.5 TeV, are presented and the assumptions and extrapolations involved are discussed.
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The phenomenological analysis of various characteristics of $J/psi$ and $D$ meson production in PbPb collisions at the center-of-mass energy 2.76 TeV per nucleon pair is presented. The data on momentum spectra and elliptic flow are reproduced by two-component model HYDJET++ including thermal and non-thermal charm production mechanisms. The significant part of $D$-mesons is found to be in a kinetic equilibrium with the created medium, while $J/psi$-mesons are characterized by earlier (as compared to light hadrons) freeze-out.
The interpretation of experimental results at RHIC and in the future also at LHC requires very reliable and realistic models. Considerable effort has been devoted to the development of such models during the past decade, many of them being heavily used in order to analyze data. It is the purpose of this paper to point out serious inconsistencies in the above-mentioned approaches. We will demonstrate that requiring theoretical self-consistency reduces the freedom in modeling high energy nuclear scattering enormously. We will introduce a fully self-consistent formulation of the multiple-scattering scheme in the framework of a Gribov-Regge type effective theory. In addition, we develop new computational techniques which allow for the first time a satisfactory solution of the problem in the sense that calculations of observable quantities can be done strictly within a self-consistent formalism.
A perturbative QCD based jet tomographic Monte Carlo model, CUJET2.0, is presented to predict jet quenching observables in relativistic heavy ion collisions at RHIC/BNL and LHC/CERN energies. This model generalizes the DGLV theory of flavor dependent radiative energy loss by including multi-scale running strong coupling effects. It generalizes CUJET1.0 by computing jet path integrations though more realistic 2+1D transverse and longitudinally expanding viscous hydrodynamical fields contrained by fits to low $p_T$ flow data. The CUJET2.0 output depends on three control parameters, $(alpha_{max},f_E,f_M)$, corresponding to an assumed upper bound on the vacuum running coupling in the infrared and two chromo-electric and magnetic QGP screening mass scales $(f_E mu(T), f_M mu(T))$ where $mu(T)$ is the 1-loop Debye mass. We compare numerical results as a function of $alpha_{max}$ for pure and deformed HTL dynamically enhanced scattering cases corresponding to $(f_E=1,2, f_M=0)$ to data of the nuclear modification factor, $R^f_{AA}(p_T,phi; sqrt{s}, b)$ for jet fragment flavors $f=pi,D, B, e$ at $sqrt{s}=0.2-2.76$ ATeV c.m. energies per nucleon pair and with impact parameter $b=2.4, 7.5$ fm. A $chi^2$ analysis is presented and shows that $R^pi_{AA}$ data from RHIC and LHC are consistent with CUJET2.0 at the $chi^2/d.o.f< 2$ level for $alpha_{max}=0.23-0.30$. The corresponding $hat{q}(E_{jet}, T)/T^3$ effective jet transport coefficient field of this model is computed to facilitate comparison to other jet tomographic models in the literature. The predicted elliptic asymmetry, $v_2(p_T;sqrt{s},b)$ is, however, found to significantly underestimated relative to RHIC and LHC data. We find the $chi^2_{v_2}$ analysis shows that $v_2$ is very sensitive to allowing even as little as 10% variations of the path averaged $alpha_{max}$ along in and out of reaction plane paths.
In order to describe forward hadron productions in high-energy nuclear collisions, we propose a Monte-Carlo implementation of Dumitru-Hayashigaki-Jalilian-Marian formula with the unintegrated gluon distribution obtained numerically from the running-coupling BK equation. We discuss influence of initial conditions for the BK equation by comparing a model constrained by global fit of small-x HERA data and a newly proposed one from the running coupling MV model.
The charmonium states with their different binding energies and radii dissolve at different temperatures of the medium produced in relativistic heavy-ion collisions. Relative yields of charmonium and thus their survival have potential to map the properties of Quark Gluon Plasma. In this study, we estimate the combined effect of color screening, gluon-induced dissociation and recombination on charmonium production in heavy-ion collisions (Pb+Pb ions) at centre of mass energy ($sqrt{s_{rm NN}}$) = 5.02 TeV. The rate equations of dissociation and recombination are solved separately with a 2-dimensional accelerated expansion of fireball volume. To solve the recombination rate equation, we have used an approach of Bateman solution which ensures the dissociation of the recombined charmonium in the QGP medium. The modifications of charmonium states are estimated in an expanding QGP with the conditions relevant for Pb+Pb collisions at LHC.
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