Metastabilities in three-flavor QCD at low quark masses

Using a Langevin algorithm to incorporate low-mass dynamical quarks, we simulate QCD with three light flavors on an $8^3$×4 lattice. We find clear metastabilities in lattice measurables at a quark mass of 0.025 in lattice units, whereas earlier analyses at 4 times the mass above did not prove their presence. Our results suggest a first-order chiral phase transition in three-flavor QCD. We also confirm the presence of a stronger first-order transition with four flavors and indicate the possibility of a weaker first-order transition with two flavors.