Computation of the Heavy-Light Decay Constant using Non-relativistic Lattice QCD

Abstract

We report results on a lattice calculation of the heavy-light meson decay constant employing the non-relativistic QCD approach for heavy quark and Wilson action for light quark. Simulations are carried out at $\beta =6.0$ on a $16^3\times 48$ lattice. Signal to noise ratio for the ground state is significantly improved compared to simulations in the static approximation, enabling us to extract the decay constant reliably. We compute the heavy-light decay constant for several values of heavy quark mass and estimate the magnitude of the deviation from the heavy mass scaling law $f_P\sqrt{m_P}=const$. For the $B$ meson we find $f_B=171\pm 22_{-45}^{+19}$ MeV, while an extrapolation to the static limit yields $f_B^{static}$ = $297\pm 36_{-30}^{+15}$ MeV.

Comments: 34 pages in LaTeX including 10 figures using epsf.sty, uuencoded-gziped-shar format, HUPD-9403