The charmed and bottom meson spectrum from lattice NRQCD

B (∗) s ) are well known experimentally, and thus provide a testing ground for the lattice method. In particular, they can be used to examine the convergence properties of the heavy quark expansion in nonrelativistic QCD (NRQCD),[1] which is the most economical lattice action available for heavy quark physics.[2] The spectrum of P-wave heavy-light mesons is not yet understood, experimentally nor theoretically, so here the lattice can offer predictions. Do the masses follow the ordering that is observed in the hydrogen atom? What are the magnitudes of the mass splittings among P-waves — tens of MeV or hundreds? Lattice studies of the P-wave spectrum have been performed for an infinitely-heavy quark[3]. A subset of the P-wave states have also been observed by using a relativistic (clover) action in the charmed region, and extrapolating to the bottom region[4]. Recently, the lattice NRQCD approach has been used to work directly with B∗∗ mesons[5–7] as well as D∗∗ mesons[5,7]. In the following sections, the lattice NRQCD method is briefly reviewed and the results of numerical simulations are presented. Implications for the convergence of the lattice NRQCD expansion are discussed, and predictions for the B∗∗ and D∗∗ mass spectra from various lattice simulations are compared to theoretical models.