S-wave charmed mesons in lattice NRQCD

Heavy-light mesons can be studied using the 1/M expansion of NRQCD, provide d the heavy quark mass is sufficiently large. Calculations of the S-wave ch armed meson masses from a classically and tadpole-improved action are prese nted. A comparison of O(1/M), O(1/M-2) and O(1/M-3) results allows converge nce of the expansion to be discussed. It is shown that the form of discreti zed heavy quark propagation must be chosen carefully.