Breaking of the number-of-constituent-quark scaling for identified-particle elliptic flow as a signal of phase change in low-energy data taken at the BNL Relativistic Heavy Ion Collider (RHIC)

TL;DR

This paper proposes that the breaking of number-of-constituent-quark scaling in elliptic flow measurements at RHIC can signal a phase transition from partonic to hadronic matter in low-energy heavy ion collisions.

Contribution

It introduces the idea that NCQ scaling breaking can serve as a signal for phase change, supported by multiphase transport model simulations across different hadronization mechanisms.

Findings

NCQ scaling is maintained in partonic phases

NCQ scaling breaks down during transition to hadronic phase

Model predicts observable differences in elliptic flow patterns

Abstract

We argue that measurements of identified-particle elliptic flow in a wide energy range could shed light on the possible phase change in high-energy heavy ion collisions at the BNL Relativistic Heavy Ion Collider (RHIC). When the hadronization process is dominated by quark coalescence, the number-of-constituent-quark (NCQ) scaling for the identified-particle elliptic flow can serve as a probe for studying the strong interacting partonic matter. In the upcoming RHIC low-energy runs, the NCQ scaling behavior may be broken because of the change of the effective degrees of freedom of the hot dense matter, which corresponds to the transition from the dominant partonic phase to the dominant hadronic phase. A multiphase transport model is used to present the dependence of NCQ scaling behavior on the different hadronization mechanisms.