Form factor ratios for B_s → K?ν and B_s → D_s?ν semileptonic decays and |V_(ub)/V_(cb)|

摘要

We present a lattice quantum chromodynamics determination of the ratio of the scalar and vector form factors for two semileptonic decays of the B_s meson: B_s → K?ν and B_s → D_s?ν. In conjunction with future experimental data, our results for these correlated form factors will provide a new method to extract |V_(ub)/V_(cb)|, which may elucidate the current tension between exclusive and inclusive determinations of these Cabibbo-Kobayashi-Maskawa mixing matrix parameters. In addition to the form factor results, we determine the ratio of the differential decay rates, and forward-backward and polarization asymmetries, for the two decays.