Study of K*(892)0 and ϕ (1020) meson production in proton–proton and Pb–Pb collisions at = 2.76 TeV

Abstract

In this paper, we describe a study of charged particle yield as a function of p T for K *(892)0 and ϕ (1020) mesons in proton–proton (pp) and Pb–Pb collisions at = 2.76 TeV in the central rapidity region of ∣y∣ < 0.5, in a p T range of 0 < p T < 15 GeV c −1 in pp collisions and in a p T range of 0 < p T < 20 GeV c −1 in Pb-Pb collisions. We also investigated a very important ratio, the nuclear modification factor, to study the effects of the medium in the most central region, i.e. 0%–5% centrality. For data simulation, we used the EPOS-LHC and EPOS-1.99 models. To check the validity of these models’ simulations, we compared the data obtained from these Monte Carlo simulation programs with ALICE experimental data for = 2.76 TeV. It was concluded that the models’ predictions for the ϕ-meson in pp and for the most central Pb-Pb collisions disagreed with the ALICE data, and that the difference increased with p T . This may be connected with the essential role of collective parton behaviors which could not have been taken into account by the models. For K *0 mesons, both programs gave almost the same predictions, and with p T in the interval p T > 3 GeV c −1, the predictions were very close to the experimental data. Both models gave higher predictions for the soft p T interval and lower predictions for the hard interactions. The values of the R AA distributions were lower than unity and both models were very close to the ALICE data. It is very interesting that the models were not able to describe the p T distributions, but they gave good predictions for their ratios. This may possibly be due to parton collective behaviors. We observed some additional suppression of K ∗0 at low values of p T with respect to ϕ-mesons, which may be related to the role of the masses of the particles in soft interactions. The rising trend for R AA in the region from p T = 10 GeV c −1 to 20 GeV c −1 observed by the ALICE experiment was absent for the ϕ-mesons.