B-SPECTROSCOPY FROM NRQCD WITH DYNAMICAL FERMIONS

We present a lattice investigation, partially including the effects of dynamical quarks, of the heavy-light mesons using NRQCD for the heavy quark and the Wilson action for the light quark, We perform an extens ive calculation of the spectrum employing a multistate, multiexponenti al fitting analysis which enables us to extract the 2S-1S splitting as well as the P-1(1)-(S) over bar and hyperfine splittings. The Wilson action introduces a large systematic error into the calculation, and w ithin this uncertainty we obtain agreement with experiment. We perform a comprehensive calculation of the heavy-light meson mass, investigat ing three methods and their range of validity. The agreement found bet ween these methods confirms that Lorentz invariance can be restored at this order in NRQCD by a constant shift to all masses. We calculated spectroscopic quantities over a wide range in heavy quark mass and are able to perform a detailed investigation of heavy quark symmetry arou nd the b quark mass. In particular, we extract the nonperturbative coe fficients of terms in the heavy quark expansion of the meson binding e nergy. We demonstrate the importance of using tadpole-improved operato rs in such a calculation.