Semi-leptonic form-factors from lattice qcd

We present results for semi-leptonic form-factors obtained on a statistical sample of $66$ $32^3 \times 64$ lattices at $\beta = 6.0$ using quenched Wilson fermions. We find $f_+^{D \to K l \nu}(q^2 = 0) = 0.73 \pm 0.06$, $A_2/A_1({D \to K^* l \nu}) = 0.72 \pm 0.22$, $V/A_1({D_s \to \phi l \nu}) = 1.91 \pm 0.04$, and $A_2/A_1({D_s \to \phi l \nu}) = 0.68 \pm 0.09$, where the error estimate includes statistical errors and errors due to extrapolation to $q^2 =0$ and to physical values of $(m_u + m_d)/2$ and $m_s$. The remaining sources of systematic errors are those due to $O(a)$ discretization errors and those due to quenching, which our results indicate may be small. We also comment on the validity of pole-dominance in these form-factors. Source available from http://nqcd.lanl.gov/Lattice_QCD/papers/dpf94/