Abstract
The increase in strangeness production with charged particle multiplicity, as seen by the ALICE collaboration at CERN in $p\text{\ensuremath{-}}p$, $p$-Pb, and Pb-Pb collisions, is investigated in the hadron resonance gas model taking into account interactions among hadrons using $S$-matrix corrections based on known phase shift analyses. Strangeness conservation is taken into account in the framework of the canonical strangeness ensemble. A very good description is obtained for the variation of the strangeness content in the final state as a function of the number of charged hadrons in the midrapidity region using the same fixed temperature value as obtained in the most central Pb-Pb collisions and with a fixed strangeness suppression factor ${\ensuremath{\gamma}}_{s}=1$. It is shown that the number of charged hadrons is linearly proportional to the volume of the system. For small multiplicities the canonical ensemble with local strangeness conservation restricted to midrapidity leads to a stronger suppression of (multi)strange baryons than seen in the data. This is compensated by introducing a global conservation of strangeness in the whole phase-space which is parametrized by the canonical correlation volume larger than the fireball volume at the midrapidity. The results on comparing the hadron resonance gas model with and without S-matrix corrections, are presented in detail. It is shown that the interactions introduced by the phase shift analysis via the $S$-matrix formalism are essential for a better description of the yields data.
Highlights
The analysis of data on hadron yields produced in heavy-ion collisions covering a broad range of energies in fixed-target and collider experiments, confirms that produced hadrons originate from a thermal fireball formed in such collisions [1,2,3,4,5,6,7,8]
We will show that the yields ofstrange baryons versus dNch/dη measured by the ALICE collaboration follow the expectations of thermal production with the canonical suppression due to exact strangeness conservation at fixed temperature T 156.5 MeV, that is consistent with the chiral crossover in lattice QCD (LQCD) and with a fixed strangeness suppression factor γs = 1
SUMMARY AND CONCLUSIONS We have studied the influence of global strangeness quantum number conservation on strangeness production in
Summary
The analysis of data on hadron yields produced in heavy-ion collisions covering a broad range of energies in fixed-target and collider experiments, confirms that produced hadrons originate from a thermal fireball formed in such collisions [1,2,3,4,5,6,7,8]. It is clear that the S-matrix scheme can improve the HRG model in approximating the QCD partition function in the hadronic phase, producing a more accurate description of the measured particle yields in heavy-ion collisions. We will show that the yields of (multi)strange baryons versus dNch/dη measured by the ALICE collaboration follow the expectations of thermal production with the canonical suppression due to exact strangeness conservation at fixed temperature T 156.5 MeV, that is consistent with the chiral crossover in LQCD and with a fixed strangeness suppression factor γs = 1. The observed scaling of hadron yields with dNch/dη for different colliding systems is a natural consequence of the HRG model with exact conservation of strangeness These results provide further evidence for the thermal origin of particle production at the LHC in p-p, p-A, and A-A collisions at a common Tf Tc. The paper is organized as follows.
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