On the existence of a phase transition for QCD with three light quarks

We report full QCD simulations on a 16{sup 3}{times}4 lattice. For two degenerate flavors no finite-temperature phase transition is found for quark masses of {ital ma}=0.01 and 0.025, where {ital a} is the lattice spacing, while for three degenerate flavors a first-order transition is easily seen for {ital ma}=0.025. Nature, with nearly massless up and down quarks and one heavier strange quark, lies between these two cases. For {ital m}{sub {ital u}},{ital d}{ital da}=0.025 and {ital m}{sub {ital s}}{ital a}=0.1 we find that {ital m}{sub {ital K}}/{ital m}{sub {rho}}=0.46(1) and that no transition occurs, calling into question the existence of a QCD phase transition.