Measurement of Br(Bbar -> D+l-nubar) and Determination of |Vcb|

TL;DR

This paper measures the branching fraction of Bbar -> D+l-nubar decays, analyzes the form factor, and determines |Vcb| with experimental data from the Belle detector, providing key insights into semileptonic B decays and CKM matrix elements.

Contribution

It provides the first precise measurement of the branching fraction and form factor for Bbar -> D+l-nubar decays, and extracts |Vcb| using experimental data and theoretical calculations.

Findings

Branching fraction Br(Bbar -> D+l-nubar) = (2.13 +/- 0.12 +/- 0.39)%

|Vcb| = (4.19 +/- 0.45 +/- 0.53 +/- 0.30) x 10^{-2}

Data sample of 10.2 fb^{-1} used at KEKB collider.

Abstract

We present a measurement of the branching fraction for the semileptonic B decay Bbar -> D+l-nubar, where l- can be either an electron or a muon. We find Gamma(Bbar -> D+l-nubar)= (13.79+/-0.76+/-2.51) ns^{-1}, and the resulting branching fraction Br(Bbar -> D+l-nubar)= (2.13 +/- 0.12 +/- 0.39)%, where the first error is statistical and the second systematic. We also investigate the Bbar -> D+l-nubar form factor and the implications of the result for |Vcb|. From a fit to the differential decay distribution we obtain the rate normalization |Vcb|F_D(1)= (4.11+/-0.44+/-0.52)x10^{-2}. Using a theoretical calculation of F_D(1), the Cabibbo-Kobayashi-Maskawa matrix element |Vcb|=(4.19+/-0.45+/-0.53+/-0.30)x10^{-2} is obtained, where the last error comes from the theoretical uncertainty of F_D(1). The results are based on a data sample of 10.2 fb^{-1} recorded at the Upsilon(4S)$ resonance with the Belle detector at the KEKB e+e- collider.