Measurement of the relative B^- →D⁰ /D^∗∗0 /D^∗∗0μ^-ν_μ branching fractions using B^- mesons from B^∗_s⁰₂ decays

The decay of the narrow resonance Bs2∗0→B-K+ can be used to determine the B- momentum in partially reconstructed decays without any assumptions on the decay products of the B- meson. This technique is employed for the first time to distinguish contributions from D0, D∗0, and higher-mass charmed states (D∗∗0) in semileptonic B- decays by using the missing-mass distribution. The measurement is performed using a data sample corresponding to an integrated luminosity of 3.0 fb-1 collected with the LHCb detector in pp collisions at center-of-mass energies of 7 and 8 TeV. The resulting branching fractions relative to the inclusive B-→D0Xμ-νμ are fD0=B(B-→D0μ-νμ)/B(B-→D0Xμ-νμ)=0.25±0.06,fD∗∗0=B(B-→(D∗∗0→D0X)μ-νμ)/B(B-→D0Xμ-νμ)=0.21±0.07, with fD∗0=1-fD0-fD∗∗0 making up the remainder.