We present a calculation of $f_B$ in the static limit, obtained by numerical simulation of quenched QCD, at $\beta=6.2$ on a $18^3 \times 64$ lattice, using the SW-Clover quark action. The decay constant has been extracted by studying heavy(static)-light correlation functions of different smeared operators, on a sample of 220 gauge field configurations. We have obtained $f_B^{ static}=(290 \pm 15 \pm 45)$ MeV, where the first error comes from the uncertainty in the determination of the matrix element and the second comes from the uncertainty in the lattice spacing. We also obtain $M_{ B_s}-M_{ B_d}= (70 \pm 10)$ MeV and $f^{ stat}_{ B_s}/f^{ stat}_{ B_d}=1.11(3)$. A comparison of our results with other calculations of the same quantity is made.
Categories: hep-ph hep-lat