Precision model-independent bounds from a global analysis of b →caν form factors

We present a model-independent global analysis of hadronic form factors for the semileptonic decays b→câ"ν that exploits lattice-QCD data, dispersion relations, and heavy-quark symmetries. The analysis yields predictions for the relevant form factors, within quantifiable bounds. These form factors are used to compute the semileptonic ratios R(Hc) and various decay-product polarizations. In particular, we find R(Ds∗)=0.20(3) and R(J/ψ)=0.25(3), predictions that can be compared to results of upcoming LHCb measurements. In developing this treatment, we obtain leading-order nonrelativistic QCD results for the nonzero-recoil relations between the Bc+→{J/ψ,ηc} form factors.