Universality of phase diagrams in QCD and QCD-like theories

TL;DR

This paper demonstrates that phase diagrams in QCD and QCD-like theories are universal across different gauge groups and chemical potentials via large-N_c equivalence, enabling new lattice studies of QCD at finite baryon density.

Contribution

It establishes the universality of phase diagrams in QCD and related theories through large-N_c equivalence, linking different chemical potentials and gauge groups.

Findings

Phase diagrams are identical between QCD at finite isospin and SO(2N_c), Sp(2N_c) gauge theories at finite baryon chemical potential.

In the chiral limit, phase diagrams match those of QCD at finite chiral chemical potential.

Universality may approximately extend to N_c=3, facilitating lattice studies of QCD at finite density.

Abstract

We show the universality of phase diagrams in QCD and QCD-like theories through the large-N_c equivalence. The whole phase diagrams are identical between QCD at finite isospin chemical potential and SO(2N_c) and Sp(2N_c) gauge theories at finite baryon chemical potential. In the chiral limit, they are also identical to that of QCD at finite chiral chemical potential. Outside the pion or diquark condensed phase in these theories, the universality of phase diagrams is applicable to QCD at finite baryon chemical potential. We further argue that the universality may work approximately even for N_c=3. Our result makes it possible to study QCD at finite baryon chemical potential and high temperature, especially the chiral phase transition, using sign-free theories on the lattice.