Recent experimental and theoretical studies suggest that the quarkonia suppression in a thermal QCD medium created at heavy ion collisions is a complex interplay of various physical processes.In this article we put together most of these processes in a unified way to calculate the charmonium survival probability (nuclear modification factor) at energies available at relativistic heavy ion collider (RHIC) and large hadron collider (LHC) experiments. We have included shadowing as the dominant cold nuclear matter (CNM) effect. Further, gluo-dissociation and collision damping have been included which provide width to the spectral function of charmonia in a thermal medium and cause the dissociation of charmonium along with usual colour screening. We include the colour screening using our recently proposed modified Chu and Matsui model. Furthermore, we incorporate the recombination of uncorrelated charm and anti-charm quark for the regeneration of charmonium over the entire temporal evolution of QGP medium. Finally we do the feed-down correction from the excited states to calculate the survival probability of charmonium. We find that our unified model suitably describes the experimental nuclear modification data of J/ψ at RHIC and LHC simultaneously.
Deconfined QCD matter in heavy-ion collisions has been a topic of paramount interest for many years. Quarkonia suppression in heavy-ion collisions at the relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) experiments indicate the quark-gluon plasma (QGP) formation in such collisions. Recent experiments at LHC have given indications of hot matter effect in asymmetric p-Pb nuclear collisions. Here, we employ a theoretical model to investigate the bottomonium suppression in Pb-Pb at √ s N N = 2.76, 5.02 TeV, and in p-Pb at √ s N N = 5.02 TeV center-of-mass energies under a QGP formation scenario. Our present formulation is based on an unified model consisting of suppression due to color screening, gluonic dissociation along with the collisional damping. Regeneration due to correlated QQ pairs has also been taken into account in the current work. We obtain here the net bottomonium suppression in terms of survival probability under the combined effect of suppression plus regeneration in the deconfined QGP medium. We mainly concentrate here on the centrality, N part and transverse momentum, p T dependence of ϒ(1S) and ϒ(2S) states suppression in Pb-Pb and p-Pb collisions at mid-rapidity. We compare our model predictions for ϒ(1S) and ϒ(2S) suppression with the corresponding experimental data obtained at the LHC energies. We find that the experimental observations on p t and N part dependent suppression agree reasonably well with our model predictions.
Results from the PHENIX experiment for the first RHIC run with Au-Au collisions at roots(NN) = 130 GeV are presented. The systematic variation with centrality of charged particle multiplicity, transverse energy, elliptic flow, identified particle spectra and yield ratios, and production of charged particles and pi(0)'s at high transverse momenta are presented. Results on two-pion correlations and electron spectra are also provided, along with a discussion of plans for the second run at RHIC.
Disciplines
Nuclear | Physics
CommentsThis is a manuscript of an article from Nuclear Physics A 698 (2002) Results from the PHENIX experiment for the first RHIC run with Au-Au collisions at √ s N N = 130 GeV are presented. The systematic variation with centrality of charged particle multiplicity, transverse energy, elliptic flow, identified particle spectra and yield ratios, and production of charged particles and π 0 's at high transverse momenta are presented. Results on two-pion correlations and electron spectra are also provided, along with a discussion of plans for the second run at RHIC.
We have estimated the dimensionless parameters such as Reynolds number (Re), Knudsen number (Kn) and Mach number (M a) for a multi-hadron system by using the excluded volume hadron resonance gas (EVHRG) model along with Hagedorn mass spectrum to include higher resonances in the system. The size dependence of these parameters indicate that the system formed in pro-ton+proton collisions may achieve thermal equilibrium making it unsuitable as a benchmark to analyze the properties of the system produced in heavy ion collisions at similar energies. While the magnitude of Kn can be used to study the degree of thermalization, the variations of Re and M a with temperature (T ) and baryonic chemical potential (µB) assist to understand the change in the nature of the flow in the system -from laminar to turbulent and from subsonic to supersonic, respectively.
Proton–nucleus collisions serve as an important baseline for the understanding and interpretation of the nucleus–nucleus collisions. These collisions have been employed to characterize the cold nuclear matter effects at SPS and Relativistic Heavy-Ion Collider energies for the past several years, as it was thought that quark–gluon plasma (QGP) is not formed in such collisions. However, at the Large Hadron Collider (LHC), there seems a possibility that QGP is formed during proton–lead (p–Pb) collisions. In this work, we have derived an expression for gluon induced excitation of
to
, using pNRQCD, and show that the relative enhancement of
vis-à-vis
, especially at high pT, gives further indication that the QGP is indeed formed in p–Pb collisions at the most central collisions at LHC energy.
and
suppression effects seen at ALICE are also qualitatively explained.
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