Probing the boundary of phase transition of nuclear matter using proton flows in heavy-ion collisions at 2-8 GeV/nucleon

TL;DR

This study uses a relativistic transport model to investigate the phase transition boundary of dense nuclear matter in heavy-ion collisions, providing constraints relevant for QCD phase diagram exploration.

Contribution

It extends the hadronic equation of state with a phase transition using the MIT bag model and constrains the phase transition boundary based on proton flow data.

Findings

Phase transition boundary is roughly 2.5-4 times saturation density.

Temperature range of the phase transition is about 64-94 MeV.

Proton flow data constrains the first-order phase transition region.

Abstract

Based on the relativistic transport model ART with the hadronic equation of state extended to have a phase transition via the use of the MIT bag model, properties of phase transition of dense nuclear matter formed in relativistic heavy-ion collisions are investigated. Proton sideward and directed flows are calculated with different equation of states in Au + Au collisions at beam energies of 2, 4, 6 and 8 GeV/nucleon. Compared with AGS experimental data in existence, the boundary of first-order phase transition is roughly confined, i.e., in the range of 2.5-4 times saturation density with temperature about 64-94 MeV. Such constraints are useful for ongoing RHIC Beam Energy Scan-II program to study the QCD matter phase diagram.