Improvement of Nf=3Nf=3 lattice QCD with Wilson fermions and tree-level improved gauge action

We determine the parameter cSWcSW required for O(a)O(a)-improvement of the three-flavor Wilson fermion action together with the tree-level Symanzik improved gauge action. The standard improvement condition is employed for a range of couplings. Additionally, we perform a check of the volume independence of cSWcSW and provide a preliminary estimate of the lattice spacing at our largest values of the gauge coupling.