Measurement of the Branching Fractions of Bbar -> D** l^- nubar_l Decays in Events Tagged by a Fully Reconstructed B Meson

TL;DR

This paper measures the branching fractions of Bbar decays to D** states with leptons, using data from the BaBar detector, confirming four D** states with high significance.

Contribution

First measurement of Bbar -> D** l^- nubar_l branching fractions using a fully reconstructed B meson technique at BaBar.

Findings

Observed four D** states with >6 sigma significance

Measured branching fractions consistent with Heavy Quark Symmetry predictions

Used invariant mass difference fits to extract signal yields

Abstract

We report a measurement of the branching fractions of Bbar -> D** l^- nubar_l decays based on 417 fb-1 of data collected at the Upsilon(4S) resonance with the BaBar detector at the PEP-II e+e- storage rings. Events are selected by fully reconstructing one of the B mesons in a hadronic decay mode. A fit to the invariant mass differences m(D(*)pi)-m(D(*)) is performed to extract the signal yields of the different D** states. We observe the Bbar -> D** l^- nubar_l decay modes corresponding to the four D** states predicted by Heavy Quark Symmetry with a significance greater than six standard deviations including systematic uncertainties.