Nonperturbative calculations of form factors for exclusive semileptonic Bs decays

We report on our determination of form factors for Bs->Ds l nu and Bs->K l nu semileptonic decays. Our calculations are based on RBC-UKQCD's gauge field ensembles and we use domain-wall fermions for up, down, strange, and charm quarks, while physical bottom quarks are simulated with the relativistic heavy quark action. Using three lattice spacings of 1/a = 1.78, 2.38, and 2.77 GeV we determine the form factors over the full q^2 range and extract R-ratios to investigate lepton flavor universality violations. In combination with experimental measurements, the ratio of our form factors for both decay processes will allow to obtain the ratio of CKM matrix elements |V_cb|/|V_ub|