The chiral critical point in 3-flavour QCD

We determine the second order endpoint of the line of first order phase tra nsitions. which occur in the light quark mass regime of 3-flavour QCD at fi nite temperature, and analyze universal properties of this chiral critical point. A detailed analysis of Binder cumulants and the joint probability di stributions of energy like and ordering-field like observables confirms tha t the chiral critical point belongs to the universality class of the three- dimensional Ising model. From a calculation with improved gauge and stagger ed fermion actions we estimate that the transition is first order for pseud o-scalar meson masses less than about 200 MeV. (C) 2001 Elsevier Science B. V. All rights reserved.