Existence of a QCD critical point at finite baryon chemical potential

Determine whether a quantum chromodynamics (QCD) critical point exists at baryon chemical potentials greater than zero, at which the hadron–to–quark–gluon plasma transition changes from a smooth crossover at μ_B=0 to a first-order phase transition.

Background

The QCD phase diagram describes the phases of strongly interacting matter as a function of temperature and baryon chemical potential. Lattice QCD establishes that at μ_B=0 the transition from hadronic matter to quark–gluon plasma is a smooth crossover, but the fermion sign problem prevents direct lattice calculations at μ_B>0, leaving the global structure of the phase diagram uncertain.

A central question for both theory and experiment is whether a true critical point exists at higher μ_B where the crossover ends and a first-order transition begins. This motivates heavy-ion collision programs and analysis methods, such as finite-size scaling, aimed at detecting signatures of critical behavior and, if present, locating the critical point.