Return of the finite-temperature phase transition in the chiral limit of lattice QCD

Lattice QCD with four flavors of light dynamical quarks is simulated on a ${10}^3$×6 lattice in order to study the finite-temperature transition in the chiral limit. The mass used, m=0.025 (in lattice units), is half the smallest value previously used on this size lattice. We find evidence for a finite-temperature phase transition which is absent for intermediate masses. The time evolution of the system shows both long correlation times characteristic of a nearby critical point and abrupt changes.