We provide a general classification of supersymmetric lattice gauge theories that can be obtained from orbifolding of theories with four and eight supercharges. We impose at least one preserved supercharge on the lattice and Lorentz invariance in the naive continuum limit. Starting with four supercharges, we obtain one two-dimensional lattice gauge theory, identical to the one already given in ...

We argue that lattice simulations of full QCD with varying quark mass are best conducted at fixed lattice spacing rather than at fixed β. We present techniques which enable this to be carried out effectively, namely the tuning in bare parameter space and efficient stochastic estimation of the fermion determinant. Results and tests of the method are presented. We discuss other applications of su...

We calculate pΞ0 potentials from the equal-time Bethe-Salpeter amplitude measured in the quenched QCD simulation with the spatial lattice volume, (4.4 fm)3. The standard Wilson gauge action with the gauge coupling β = 5.7 on 324 lattice together with the standard Wilson quark action are used. The hopping parameter κud = 0.1678 is chosen for u and d quarks, which corresponds to mπ ≃ 0.37 GeV. Th...

We determine the topological susceptibility χ t in the topologically-trivial sector generated by lattice simulations of N f = 2 + 1 QCD with overlap Dirac fermion, on a 16 3 × 48 lattice with lattice spacing ∼ 0.11 fm, for five sea quark masses m q ranging from m s /6 to m s (where m s is the physical strange quark mass). The χ t is extracted from the plateau (at large time separation) of the 2...

We determine the sphaleron transition rate using real time lattice simulations of the classical system. An improved definition of the lattice topological charge allows us to obtain a more reliable estimate of the transition rate. For an SU(2) Yang-Mills-Higgs system in the broken phase we find the transition rate to be strongly suppressed, and we have observed no sphaleron transitions in the ra...

We determine the chiral condensate from simulations of quenched lattice QCD with Wilson fermions. Our measurements have been obtained with high statistics at three values of the gauge coupling, corresponding to UV cutoffs in the range 2− 4 GeV. Several improvements have been made with respect to earlier lattice computations. The most important are the non-perturbative renormalization of the con...

We report on first results of an ongoing effort to simulate lattice QCD with two degenerate flavours of quarks by means of the twisted mass formulation tuned to maximal twist. By utilising recent improvements of the HMC algorithm, pseudo-scalar masses well below 300MeV are simulated on volumes L3 · T with T = 2L and L > 2fm and at values of the lattice spacing a . 0.1fm. We present first eviden...

We discuss the current status of our calculation of the physics of π and K mesons using three dynamical flavors of improved staggered quarks. This year, we have a new ensemble with a lattice spacing of 0.06 fm and a light sea mass of 0.2ms, as well as significant increases in statistics at several coarser lattice spacings and/or heavier sea masses. Results for decay constants, quark masses, low...

We study the effects of additional fields on the unification of gauge couplings in supersymmetric models. We find that the effects are quite constrained by the requirement of SU(5) gauge invariance. In general, we find that any extension of the MSSM will form complete SU(5) multiplets or spoil gauge coupling unification.

We report results on the static quark potential in two-flavor full QCD. The calculation is performed for three values of lattice spacing a 3 ×48 lattices respectively, at sea quark masses corresponding to mπ/mρ ≈ 0.8–0.6. An RG-improved gauge action and a tadpole-improved SW clover quark action are employed. We discuss scaling of mρ/ √ σ and effects of dynamical quarks on the potential.