Andrew Lytle (University of Glasgow)
We use both non-relativistic QCD (NRQCD) and fully relativistic formalisms to calculate semileptonic form factors for the decays B_c -> eta_c lv and B_c -> J/psi lv over the entire q^2 range. To achieve this we employ a highly improved lattice quark action and at several lattice spacings down to a=.044 fm, which allow a fully relativistic treatment of charm and simulation of the full q^2 range with controlled continuum extrapolation. We have two ways of treating the b quark: either with an O(alpha_s) improved NRQCD formalism or by extrapolating a heavy mass m_h to m_b in the relativistic formalism. We find good agreement between these approaches which provides an important cross-check of our results.