R(J/Psi) And B-C(-) -> J/Psi L(Nu)Over-Bar(L) Lepton Flavor Universality Violating Observables From Lattice Qcd

We use our lattice QCD computation of the B-c -> J/psi form factors to determine the differential decay rate for the semitauonic decay channel and construct the ratio of branching fractions R(J/psi) = B(B-c(-) -> J/psi tau(-)(nu) over bar (tau)) B(B-c(-) -> J/psi mu(-)(nu) over bar (mu)). We find R(J/psi) = 0.2582(38) and give an error budget. We also extend the relevant angular observables, which were recently suggested for the study of lepton flavor universality violating effects in B -> D*l nu, to B-c -> J/psi l nu and make predictions for their values under different new physics scenarios.