The QCD Phase Diagram at Non-zero Baryon and Isospin Chemical Potentials

TL;DR

This paper uses a random matrix model to show that even small isospin chemical potentials significantly alter the QCD phase diagram, introducing multiple phase transitions and critical points relevant for heavy ion collisions.

Contribution

It demonstrates how small isospin chemical potentials impact the QCD phase diagram, revealing complex phase transition structures not previously detailed.

Findings

Two first order phase transitions at low temperature

Two critical endpoints identified

Two crossovers at high temperature

Abstract

In heavy ion collision experiments as well as in neutron stars, both baryon and isospin chemical potentials are different from zero. In particular, the regime of small isospin chemical potential is phenomenologically important. Using a random matrix model, we find that the phase diagram at non-zero temperature and baryon chemical potential is greatly altered by an arbitrarily small isospin chemical potential: There are two first order phase transitions at low temperature, two critical endpoints, and two crossovers at high temperature. As a consequence, in the region of the phase diagram explored by RHIC experiments, there are two crossovers that separate the hadronic phase from the quark-gluon plasma phase at high temperature.