Abstract
We calculate volume-independent ratios of cumulants of the net-proton number distribution up to sixth order in a fireball that cools down after the chemical freeze-out. A hadron resonance gas model is used together with the assumption of partial chemical equilibrium, which fixes the number of observed stable hadrons after the chemical freeze-out. It is shown that, due to only weak departure from the statistical Boltzmann distribution, also the volume-independent ratios of higher-order cumulants of the net-proton number show only weak dependence on the temperature. This observation supports the possibility to measure noncritical cumulants at chemical freeze-out even after subsequent cooling in the hadronic phase. Cumulants of the net-baryon number behave similarly, while those for the kaon number vary more strongly with the temperature. Our results are relevant for the current fluctuation studies of runs of the Beam Energy Scan program at the BNL Relativistic Heavy Ion Collider.
1 More- Received 13 July 2021
- Revised 31 August 2021
- Accepted 8 October 2021
DOI:https://doi.org/10.1103/PhysRevC.104.044907
©2021 American Physical Society