Nonperturbative O(a) improvement of the Wilson quark action with the renormalization-group-improved gauge action using the Schrödinger functional method

University of Tsukuba, Tsukuba, Ibaraki, Japan
Physical review D: Particles and fields (Impact Factor: 4.86). 02/2006; 73(3). DOI: 10.1103/PhysRevD.73.034501
Source: arXiv

ABSTRACT We perform a nonperturbative determination of the O(a)-improvement coefficient cSW and the critical hopping parameter kappac for Nf=3, 2, and 0 flavor QCD with the (RG) renormalization-group-improved gauge action using the Schrödinger functional method. In order to interpolate cSW and kappac as a function of the bare coupling, a wide range of beta from the weak coupling region to the moderately strong coupling points used in large-scale simulations is studied. Corrections at finite lattice size of O(a/L) turned out to be large for the RG-improved gauge action, and hence we make the determination at a size fixed in physical units using a modified improvement condition. This enables us to avoid O(a) scaling violations which would remain in physical observables if cSW determined for a fixed lattice size L/a is used in numerical simulations.

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