Towards a theoretical description of dense QCD

TL;DR

This paper reviews effective lattice theories derived from strong coupling expansions to describe dense QCD, addressing the sign problem and capturing key nuclear physics features like the liquid-gas transition.

Contribution

It introduces and discusses effective lattice theories based on strong coupling methods that approximate dense QCD and reproduce essential nuclear phenomena.

Findings

Effective theories can model nuclear matter properties from QCD.

Nuclear liquid-gas transition is captured by the models.

Equation of state for baryons derived from QCD.

Abstract

The properties of matter at finite baryon densities play an important role for the astrophysics of compact stars as well as for heavy ion collisions or the description of nuclear matter. Because of the sign problem of the quark determinant, lattice QCD cannot be simulated by standard Monte Carlo at finite baryon densities. I review alternative attempts to treat dense QCD with an effective lattice theory derived by analytic strong coupling and hopping expansions, which close to the continuum is valid for heavy quarks only, but shows all qualitative features of nuclear physics emerging from QCD. In particular, the nuclear liquid gas transition and an equation of state for baryons can be calculated directly from QCD. A second effective theory based on strong coupling methods permits studies of the phase diagram in the chiral limit on coarse lattices.