Incorporating dynamical Kogut-Susskind fermions into a Monte Carlo simulation of QCD, we have analyzed the masses of low-lying hadrons, chiral-symmetry breaking, and the interquark potential. We used a 24X 12' lattice for two couplings g, where 8=6/g2=5.20 and 5.35. The quark masses were ma =0.075, 0.050, and 0.025 (a being the lattice spacing). We find that the pattern of hadron masses of the T , p, and N is qualitatively as seen experimentally. The pion mass squared is proportional to the quark mass and thus behaves as expected from chiral symmetry. Values for the quark condensate extrapolated to ma =0, the renormalization-group-invariant quark mass, and the pion decay constant are in reasonable agreement with values derived from experiment or from current algebra. If we fix the lattice spacing from the p mass, we see evidence for the screening effect of light-quark-antiquark pairs in the potential between two massive quarks. At 8=5.20 and ma =0.050 we find good agreement between the results from our pseudofermion method and those from a hybrid simulation.

We present results for static hadronic correlation functions in the high-temperature phase of QCD with four flavors of dynamical quarks. We confirm chiral-symmetry restoration through the degeneracies of the spectrum of screening lengths. We also find that the screening lengths for the p and TV channels at rS; 1.27V are close to that in a free quark gas. PACS numbers: 12.38.Gc, 12.38.Mh Simulations of lattice QCD have shown that chiral symmetry is restored at high temperatures, as indicated by the vanishing of the chiral order parameter (##> [1].Additional evidence for the restoration of chiral symmetry can be obtained by using hadronic correlation functions, first studied by DeTar and Kogut [2]. The exponential falloff of such correlations at large spatial separations determines screening lengths, and unbroken symmetries are reflected in degeneracies of these screening lengths. Hadronic correlation functions also yield information on the real-time modes of the high-temperature phase. If the plasma phase contains hadronic modes, as argued by DeTar and Kogut [2], then the corresponding correlation functions should be screened. On the other hand, free quarks also lead to screening in the imaginary-time formulation-through the existence of a finite infrared cutoff on the Euclidean-time components of momenta. It is therefore important to determine the temperature dependence of these screening lengths and to compare them with the results of a computation with free quarks.In this Letter we present results for hadronic correlations obtained on an 8xl6 3 lattice with four flavors of dynamical quarks of mass m q a =0.01, and compare them to values obtained for a gas of free quarks, taking into account finite-size effects in the latter case. We performed measurements on configurations generated by the MT C Collaboration with the hybrid Monte Carlo algorithm (see Ref.[3] for details of the runs), using approximately twenty configurations at each /?, separated by about fifty trajectories, in order to take care of autocorrelations. At /3=5.15 (our estimate for fi c ), where two runs from different starts indicated the presence of metastabilities, we made separate analyses for the two.We restrict our analysis to spatial correlations between local hadronic operators constructed from staggered fermions. The construction of static correlation functions uses methods familiar from mass spectrum analysis at zero temperature [4]. We use a notation common for the corresponding zero-temperature correlations: Afps, Msc, MVT, and Afpv for the meson correlations and B for the baryon correlation [5]. We measured correlations in the z direction. To compensate for antiperiodicity in the imaginary-time direction r, we replaced the temporal average in B by Biz)-X cos(cooT)B(x,y,z y r),x,y,r where coo =7rT is the lowest Matsubara frequency. It is possible to test for chiral-symmetry restoration directly from the correlation functions without extracting screening masses. Following Ref.[6], we construct for this purpose the chiral projections M 0...