Centrality dependence of J/ψ and ψ(2S) production and nuclear modification in p-Pb collisions at $$ \sqrt{s_{\mathrm{NN}}} $$ = 8.16 TeV

The inclusive production of the J/ψ and ψ(2S) charmonium states is studied as a function of centrality in p-Pb collisions at a centre-of-mass energy per nucleon pair $$ \sqrt{s_{\mathrm{NN}}} $$ s NN = 8.16 TeV at the LHC. The measurement is performed in the dimuon decay channel with the ALICE apparatus in the centre-of-mass rapidity intervals −4.46 < ycms< −2.96 (Pb-going direction) and 2.03 < ycms< 3.53 (p-going direction), down to zero transverse momentum (pT). The J/ψ and ψ(2S) production cross sections are evaluated as a function of the collision centrality, estimated through the energy deposited in the zero degree calorimeter located in the Pb-going direction. The pT-differential J/ψ production cross section is measured at backward and forward rapidity for several centrality classes, together with the corresponding average 〈pT〉 and $$ \left\langle {p}_{\mathrm{T}}^2\right\rangle $$ p T 2 values. The nuclear effects affecting the production of both charmonium states are studied using the nuclear modification factor. In the p-going direction, a suppression of the production of both charmonium states is observed, which seems to increase from peripheral to central collisions. In the Pb-going direction, however, the centrality dependence is different for the two states: the nuclear modification factor of the J/ψ increases from below unity in peripheral collisions to above unity in central collisions, while for the ψ(2S) it stays below or consistent with unity for all centralities with no significant centrality dependence. The results are compared with measurements in p-Pb collisions at $$ \sqrt{s_{\mathrm{NN}}} $$ s NN = 5.02 TeV and no significant dependence on the energy of the collision is observed. Finally, the results are compared with theoretical models implementing various nuclear matter effects.

Identifying hadronic charmonium decays in hadron colliders

Identification of charmonium states at hadron colliders has mostly been limited to leptonic decays of the J/\psiJ/ψ. In this paper we present an algorithm to identify hadronic decays of charmonium states (J/\psiJ/ψ, \psiψ(2S), \chi_{c0,c1,c2}χc0,c1,c2) which make up the large majority of all decays. The algorithm is able to identify hadronic J/\psiJ/ψ decays with an efficiency of 36% while suppressing a background of quark and gluon jets by a factor 100.

Equation of States and Charmonium Suppression in Heavy-Ion Collisions

The present article is the follow-up of our work Bottomonium suppression in quasi-particle model, where we have extended the study for charmonium states using quasi-particle model in terms of quasi-gluons and quasi quarks/antiquarks as an equation of state. By employing medium modification to a heavy quark potential thermodynamic observables, viz., pressure, energy density, speed of sound, etc. have been calculated which nicely fit with the lattice equation of state for gluon, massless, and as well massive flavored plasma. For obtaining the thermodynamic observables we employed the debye mass in the quasi particle picture. We extended the quasi-particle model to calculate charmonium suppression in an expanding, dissipative strongly interacting QGP medium (SIQGP). We obtained the suppression pattern for charmonium states with respect to the number of participants at mid-rapidity and compared it with the experimental data (CMS JHEP) and (CMS PAS) at LHC energy (Pb+Pb collisions, sNN = 2.76 TeV).

Prospects of Ξ(1530)0Ξ̄(1530)0pair production at BESIII

The study of the baryon–antibaryon pair production from the charmonium states provides a favorable test and an input for the perturbative quantum chromodynamics calculation. Based on a Monte Carlo study via a single tag baryon strategy, a clear observation of [Formula: see text](3686)[Formula: see text](1530)[Formula: see text](1530)0is predicted at BESIII with the current 3.08[Formula: see text]106[Formula: see text](3686) dataset. The averaged precision of the [Formula: see text] parameters in the decay angular distribution formula is estimated as 0.25, and is not effective to separate the theoretical predictions. It will be an opportunity to distinguish them with 3.0[Formula: see text]109[Formula: see text](3686) events taken by BESIII detector in the next few years.

Charmonium at BESIII

With large J/ψ and ψ(2S ) data samples, the BESIII Collaboration has performed many studies toward conventional charmonium states below energy 3.686 GeV, which provide information on the internal structure and the interactions of the mesons. In this proceeding, just a few of them, related to (1) OZI suppressed decay search or measurement, (2) “12% rule” test, and (3) theoretical different predictions test, is focused on.