Additional Strange Hadrons from QCD Thermodynamics and Strangeness Freeze-out in Heavy Ion Collisions

TL;DR

This study compares lattice QCD results with hadron resonance gas models to identify additional strange hadrons, revealing their impact on strange hadron yields and lowering freeze-out temperature estimates.

Contribution

It demonstrates that supplementing HRG models with uncharted strange hadrons improves agreement with lattice QCD and affects freeze-out temperature determinations.

Findings

Conventional HRG models fail near QCD crossover.

Adding predicted strange hadrons improves thermodynamic descriptions.

Ground-state strange baryon freeze-out temperatures decrease by 5-8 MeV.

Abstract

We compare lattice QCD results for appropriate combinations of net strangeness fluctuations and their correlations with net baryon number fluctuations with predictions from two hadron resonance gas (HRG) models having different strange hadron content. The conventionally used HRG model based on experimentally established strange hadrons fails to describe the lattice QCD results in the hadronic phase close to the QCD crossover. Supplementing the conventional HRG with additional, experimentally uncharted strange hadrons predicted by quark model calculations and observed in lattice QCD spectrum calculations leads to good descriptions of strange hadron thermodynamics below the QCD crossover. We show that the thermodynamic presence of these additional states gets imprinted in the yields of the ground-state strange hadrons leading to a systematic 5--8 MeV decrease of the chemical freeze-out temperatures of ground-state strange baryons.