A high statistics lattice calculation of ƒB in the static limit on APE

Abstract We present a high statistics calculation of ƒ B in the static limit. The results have been obtained by numerical simulation of quenched QCD, at β = 6.0 on a 18 3 × 32 lattice. We compare ƒ B calculated by using the Wilson and the Clover quark actions. The decay constant is obtained by studying heavy-light correlation functions of different smeared operators, on a sample of 210 gauge field configurations. We find that cubic smearings of size L s ⩽ 3 or L s ⩾ 9 are bad projectors on the lightest pseudoscalar state. Combining the information coming from smearing L s = 5 and L s = 7, we have obtained ƒ B = 370±40 MeV in the clover case and ƒ B = 350±40±30 MeV in the Wilson case. Our results support a large value of the pseudoscalar decay constant in the static approximation.