The results of an exploratory lattice study of heavy baryon spectroscopy are presented. We have computed the full spectrum of the eight baryons containing a single heavy quark, on a 24 3 × 48 lattice at β = 6.2, using an O(a)-improved fermion action.We discuss the lattice baryon operators and give a method for isolating the contributions of the spin doublets (Σ, Σ * ), (Ξ ′ , Ξ * ) and (Ω, Ω * ) to the correlation function of the relevant operator. We compare our results with the available experimental data and find good agreement in both the charm and the beauty sectors, despite the long extrapolation in the heavy quark mass needed in the latter case. We also predict the masses of several undiscovered baryons. We compute the Λ − pseudoscalar meson and Σ − Λ mass splittings. Our results, which have errors in the range 10 − 30%, are in good agreement with the experimental numbers. For the Σ * − Σ mass splitting, we

We present the results of a high statistics lattice study of the gluon propagator, in the Landau gauge, at β = 6.0. As suggested by previous studies, we find that, in momentum space, the propagator is well described by the expression G(k 2 ) = M 2 + Z · k 2 (k 2 /Λ 2 ) η −1 . By comparing G(k 2 ) on different volumes, we obtain a precise determination of the exponent η = 0.532(12), and verify that M 2 does not vanish in the infinite volume limit. The behaviour of η and M 2 in the continuum limit is not known, and can only be studied by increasing the value of β.

We present results of a lattice analysis of the B parameter B B , the decay constant f B , and several mass splittings using the static approximation. Results were obtained for 60 quenched gauge configurations computed at ␤ϭ6.2 on a lattice size of 24 3 ϫ48. Light quark propagators were calculated using the O(a)-improved Sheikholeslami-Wohlert action. We findcorresponding to B B static ϭ1.02 Ϫ6 Ϫ2 ϩ5 ϩ3 , f B static ϭ266 Ϫ20 Ϫ27 ϩ18 ϩ28 MeV, and f B s 2 B B s / f B 2 B B ϭ1.34 Ϫ8 Ϫ3 ϩ9 ϩ5 , where a variational fitting technique was used to extract f B static . For the mass splittings we obtain M B s ϪM B d ϭ87 Ϫ12 Ϫ12 ϩ15 ϩ6 MeV, M ⌳ b ϪM B d ϭ420 Ϫ90 Ϫ30 ϩ100 ϩ30 MeV, and M B* 2 ϪM B 2 ϭ0.281 Ϫ16 Ϫ37 ϩ15 ϩ40 GeV 2 . We compare different smearing techniques in-tended to improve the signal/noise ratio. From a detailed assessment of systematic effects, we conclude that the main systematic uncertainties are associated with the renormalization constants relating a lattice matrix element to its continuum counterpart. The dependence of our findings on lattice artifacts is to be investigated in the future. ͓S0556-2821͑96͒04715-7͔

No abstract

A hybrid lattice Boltzmann method (LBM) for binary mixtures based on the free-energy approach is proposed. Non-ideal terms of the pressure tensor are included as a body force in the LBM kinetic equations, used to simulate the continuity and Navier-Stokes equations. The convectiondiffusion equation is studied by finite difference methods. Differential operators are discretized in order to reduce the magnitude of spurious velocities. The algorithm has been shown to be stable and reproducing the correct equilibrium behavior in simple test configurations and to be Galilean invariant. Spurious velocities can be reduced of about an order of magnitude with respect to standard discretization procedure.