Particle production at energies available at the CERN Large Hadron Collider within an evolutionary model

Abstract

The particle yields and particle number ratios in Pb+Pb collisions at the CERN Large Hadron Collider (LHC) energy √ s NN = 2.76 TeV are described within the integrated hydrokinetic model (iHKM) at two different equations of state (EoS) for quark-gluon matter and the two corresponding hadronization temperatures T = 165 MeV and T = 156 MeV. The role of particle interactions at the final afterburner stage of the collision in the particle production is investigated by means of comparison of the results of full iHKM simulations with those where the annihilation and other inelastic processes (except for resonance decays) are switched off after hadronization/particlization, similarly as in the thermal models. An analysis supports the picture of continuous chemical freeze-out in the sense that the corrections to the sudden chemical freeze-out results, which arise because of the inelastic reactions at the subsequent evolution times, are noticeable and improve the description of particle number ratios. An important observation is that, although the particle number ratios with switched-off inelastic reactions are quite different at different particlization temperatures which are adopted for different equations of state to reproduce experimental data, the complete iHKM calculations bring very close results in both cases.

Bulk observables in Pb+Pb collisions at sNN=5.02TeV at the CERN Large Hadron Collider within the integr

“…for certain ratios in the latter "reduced" mode can noticeably differ for the two particlization temperatures, the full calculation always gives very close values in both cases. This peculiarity in results is in accordance with that observed and discussed in our previous work [8]. The compensatory mechanism, eliminating in the "full" mode the difference, observed between the ratios at the two EoS/T p 's in the "reduced" mode, is associated with inelastic reactions in the hadronic cascade, which last longer at a higher particlization temperature.…”

“…Thus, the obtained results for Pb + Pb collisions at √ s NN = 5.02 TeV allow us to confirm and extend an impor-tant conclusion, made in Ref. [8] basing only on the analysis of particle number ratios at √ s NN = 2.76 TeV-the multiple hadronic rescatterings at the final stage of the collision play a vital role in formation of all the bulk observables and compensate the changes introduced to the system's evolution by switching to another EoS for (quasi)thermalized matter, used at the hydrodynamic stage, and another hadronization temperature.…”

“…8, one sees that the latter discrepancy is due to overestimation of the K * yield in the model-its value is approximately twice higher in iHKM than in the experiment. This fact looks strange, since in our recent study [8], focused on the particle production in the LHC Pb + Pb collisions at lower energy, √ s NN = 2.76 TeV, we obtained a good agreement between model K * yield (and K * /K ratio) description and the corresponding ALICE data. Note that in our simulations we accounted also for possible problems with the K * identification through the products of its decay into kaons and pions, which could be caused by the interaction of these daughter particles with the surrounding hadronic medium.…”

“…Here we are going to investigate whether the crucial observation made in Ref. [8], as for the possibility to get equally good data description at both EoS/T p s if the 0 (τ 0 ) parameter is correspondingly adjusted, can be confirmed at higher energy and for all the observables, including not only particle yields, but also spectra, elliptic flow, femtoscopy radii, etc. Thus, in this paper iHKM is for the first time applied to the study of collisions at the recently achieved highest LHC energy, 5.02 A TeV.…”

Description of bulk observables in Au+Au collisions at top RHIC energy in the integrated hydrokinetic model

“…Previously, the Au+Au collisions at the top RHIC energy were successfully simulated in the hydrokinetic model [3][4][5], the model-predecessor of the modern, more developed iHKM, which proved to be good in describing observables at the LHC energies [1,6,7]. Here we aim to adjust the iHKM to the description of yields, p T spectra, interferometry radii, etc.…”