Symmetry Energy Effects on the Mixed Hadron-Quark Phase at High Baryon Density

TL;DR

This paper investigates how symmetry energy influences the hadron-quark phase transition at high densities, highlighting observable isospin effects relevant for upcoming heavy ion collision experiments.

Contribution

It introduces a detailed analysis of isospin effects on the mixed hadron-quark phase, emphasizing their robustness and potential experimental signatures.

Findings

Isospin asymmetry lowers the transition boundary, making the mixed phase accessible in future experiments.

Significant isospin effects manifest as an 'Isospin Distillation' in the quark phase.

Observable signals include charged meson ratios and quark number scaling in flow measurements.

Abstract

The phase transition of hadronic to quark matter at high baryon and isospin density is analyzed. Relativistic mean field models are used to describe hadronic matter, and the MIT bag model is adopted for quark matter. The boundaries of the mixed phase and the related critical points for symmetric and asymmetric matter are obtained. Due to the different symmetry term in the two phases, isospin effects appear to be rather significant. With increasing isospin asymmetry the binodal transition line of the (T,\rho_B) diagram is lowered to a region accessible through heavy ion collisions in the energy range of the new planned facilities, e.g. the FAIR/NICA projects. Some observable effects are suggested, in particular an "Isospin Distillation" mechanism with a more isospin asymmetric quark phase, to be seen in charged meson yield ratios, and an onset of quark number scaling of the meson/baryon elliptic flows. The presented isospin effects on the mixed phase appear to be robust with respect to even large variations of the poorly known symmetry term at high baryon density in the hadron phase. The dependence of the results on a suitable treatment of isospin contributions in effective QCD Lagrangian approaches, at the level of explicit isovector parts and/or quark condensates, is finally discussed.