Testing the phase transition parameters inside neutron stars with the production of protons and lambdas in relativistic heavy-ion collisions

TL;DR

This study compares phase transition parameters in neutron stars and heavy-ion collisions, using proton and lambda flow data to constrain the high-density quark matter equations of state.

Contribution

It demonstrates the consistency of phase transition parameters across neutron stars and heavy-ion collisions and constrains the high-density quark matter equations of state using flow data.

Findings

Proton flow at 3 GeV/nucleon favors a low phase transition density below 2.5 times saturation density.

Proton flow at 4.5 GeV/nucleon constrains the softness of high-density quark matter.

Lambda flow is less sensitive and does not effectively constrain the equations of state.

Abstract

We demonstrate the consistency of the quark deconfinement phase transition parameters in the beta-stable neutron star matter and in the nearly symmetric nuclear matter formed in heavy-ion collisions (HICs). We investigate the proton and $\Lambda$ flow in Au+Au collisions at 3 and 4.5 GeV/nucleon incident beam energies with the pure hadron cascade version of a multi-phase transport model. The phase transition in HICs and neutron stars is described based on a class of hybrid equations of state from the quark mean-field model for the hadronic phase and a constant-speed-of-sound parametrization for the high-density quark phase. The measurements of the anisotropic proton flow at 3 GeV/nucleon by the STAR collaboration favor a relatively low phase transition density lower than $\sim 2.5$ times saturation density indicated by the gravitational wave and electromagnetic observations of neutron stars. And the proton flow data at the higher energy of 4.5 GeV/nucleon can be used to effectively constrain the softness of high-density quark matter equations of state. Finally, compared to the proton flow, the $\Lambda$ flow is found to be less sensitive and not constraining to the equations of state.