Quest for more information from lattice QCD simulations

Lattice QCD is one of the most powerful tools to study the non-perturbative nature of the strong interaction. Although much information has been obtai ned so far to understand QCD, the computational cost becomes higher and hig her as we calculate on finer lattices; simulations near the continuum are s till far beyond. We report the progress on (1) renormalization group (RG) improved actions a nd (2) anisotropic lattice, which QCD-TARO group has developed and studied in order to get more information from the simulations on the present comput ers. RG improved actions were proposed and studied by Wilson (1)) and Iwasaki(2) ) to remove discretization effects for long distance observables. We have s tudied I x 1 + 1 x 2 type actions, which includes Wilson, Symanaik and Iwas aki ones, by the strong and weak coupling expansions and Monte Carlo RG met hod. We have calculated RG flow and obtained a new effective beta-function. Anisotropic lattice, where the temporal lattice spacing is smaller than tha t along the spatial one, makes us possible to perform finer resolution meas urements in the temporal direction, This is especially useful at the finite temperature, where the temporal lattice size is limited. We have calculate d mason pole and screening masses. Wie have found they behave in a differen t manner as a function of T.