Non-equilibrium components in very low transverse momentum region in high-energy nuclear collisions

TL;DR

This paper investigates the role of non-equilibrium components in very low transverse momentum regions of high-energy Pb+Pb collisions, highlighting their impact on particle correlations and the interpretation of quark-gluon plasma properties.

Contribution

It introduces a novel framework combining equilibrium and non-equilibrium particle production, emphasizing the significance of non-equilibrium effects at low transverse momentum.

Findings

Non-equilibrium components significantly influence low-$p_T$ particle production.

Non-equilibrium effects alter four-particle cumulant measurements.

Results suggest the importance of including non-equilibrium components in quark-gluon plasma studies.

Abstract

We analyze Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV with a novel framework based on the dynamical core--corona picture that describes particle productions from both equilibrium and non-equilibrium components. We remark the possibility of the contribution from non-equilibrium components at very low transverse momentum ($p_{T}$) region and show that such contributions significantly affect $p_{T}$-integrated four-particle cumulants. These results strongly suggest the necessity of non-equilibrium components when one extracts properties of the quark-gluon plasma from experimental data using sophisticated dynamical models based on relativistic hydrodynamics.