Sequential melting of charmonium states in an expanding quark–gluon plasma andJ/ψ suppression at RHIC and LHC energy collisions

Abstract

We have developed a hydrodynamic model to study sequential melting of charmonium states in an expanding QGP medium. According to the initial fluid temperature profile, J/ψ's are randomly distributed in the transverse plane. As the fluid evolve in time, the free streaming J/ψ's are suppressed if the local fluid temperature exceeds a critical temperature. PHENIX data on the centrality dependence of J/ψ suppression in Au+Au collisions at mid-rapidity are explained by sequential melting of the charmonium states, χc, ψ′ and J/ψ, in the expanding medium. The critical temperatures T J/ψ ≈ 2.09Tc and Tχ = Tχ c = T ψ′ ≈ 1.1Tc agree with lattice motivated calculations. The feed-down fraction F depend on whether the cold nuclear matter effect is included or not. It changes from F = 0.3 with cold nuclear matter effect included to F = 0.5 when the effect is neglected. Model fails to reproduce the PHENIX data on the centrality dependence of J/ψ suppression in Cu+Cu collisions at mid-rapidity, indicating that the mechanism of J/ψ suppression is different in Au+Au and in Cu+Cu collisions. We also use the model to predict for the centrality dependence of J/ψ suppression in Pb+Pb collisions at LHC energy, √ s=5500 GeV. In LHC energy, J/ψ's are more suppressed in mid central collisions than in Au+Au collisions at RHIC energy. PACS numbers: PACS numbers: 25.75.-q, 25.75.Dw

Analysing $j/Ψ$ Production in Various RHIC Interactions with a Version of Sequential Chain Model (SCM)

“…The data are taken from [31], [38]. The SCM-based result is compared with other theoretical results (a) Coalescence and Direct approaches [38] and (b)'hydro+J/Ψ' for T J/Ψ /T C = 1.2 and 1.4(hydro+J/Psi1, hydro+J/Psi2 respectively) [37], and PQCD from Ref. [39] in the Figures.…”

“…The solid line in that figure gives the SCM-based results. The dotted lines in Figure 12 show the hydrodynamical ('Hydro+J/Ψ') model-based calculations with and without nuclear absorption ('hydro+j/Psi 1' and 'hydro+J/Psi 2' respectively) [37]. And for the Au + Au collisions, the data in Figures 13(a) and (b) are taken from [31], [38].…”