Strangeness freeze-out: role of system size and missing resonances

¹ AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow, Poland
² Institute of Particle Physics and Key Laboratory of Quark & Lepton Physics (MOE), Central China Normal University, Wuhan - 430079, China
³ National Institute of Science Education and Research, HBNI, Jatni - 752050, India

^* e-mail: Sandeep.Chatterjee@fis.agh.edu.pl

Published online: 2 February 2018

Abstract

The conventional approach to treat strangeness freezeout has been to consider a unified freezeout scheme where strangeness freezes out along with the nonstrange hadrons (1CFO), with or without an additional parameter accounting for out-of-equilibrium strangeness production (γ_S). Several alternate scenarios have been formulated lately. Here, we will focus on flavor dependent freezeout with early freezeout of strangeness (2CFO) in comparison to 1CFO and its variants with respect to the roles played by the system size and missing resonances predicted by different theoretical approaches but yet to be seen in experiments. In contrast to the performance of 1CFO with/without γ_S that is insensitive to system size, 2CFO exhibits a clear system size dependence-while for Pb+Pb the χ²/NDF is around 0-2, for smaller system size in p+Pb and p+p, the χ²/NDF> 5 and larger than 1CFO+γ_S. This clearly shows a system size dependence of the preference for the freezeout scheme, while 2CFO is preferred in Pb+Pb, 1CFO+γ_S is preferred in p+Pb and p+p. We have further investigated the role of the missing resonances on strangeness freezeout across SPS to LHC beam energies.