Conserved charge fluctuations are not conserved during the hadronic phase

TL;DR

This study uses simulations to show that hadronic rescattering significantly alters charge fluctuation correlations, challenging the idea that final measurements directly reflect earlier QCD crossover conditions.

Contribution

It demonstrates through UrQMD simulations that charge fluctuation correlations are not conserved during the hadronic phase, questioning previous assumptions about their direct link to early-stage conditions.

Findings

Hadronic rescattering weakens charge correlation signals.

Final distributions do not reliably reflect earlier QCD crossover states.

Simulations challenge the paradigm of direct correlation between final and initial charge fluctuations.

Abstract

We study the correlation between the distributions of the net-charge, net-kaon, net-baryon and net-proton number at hadronization and after the final hadronic decoupling by simulating ultra relativistic heavy ion collisions with the hybrid version of the ultrarelativistic quantum molecular dynamics (UrQMD) model. We find that due to the hadronic rescattering these distributions are not strongly correlated. The calculated change of the correlation, during the hadronic expansion stage, does not support the recent paradigm, namely that the measured final moments of the experimentally observed distributions do give directly the values of those distributions at earlier times, when the system had been closer to the QCD crossover.