A Measurement of Semileptonic B Decays to Narrow Orbitally-Excited Charm Mesons

TL;DR

This paper measures the branching ratios of semileptonic B decays to narrow orbitally-excited charm mesons using data from Z decays, providing new experimental insights into these decay channels.

Contribution

It presents the first measurement of the branching ratio for B decays to the D_1^0 state and sets an upper limit for decays to the D_2^{*0} state, advancing understanding of B meson decay dynamics.

Findings

Measured BR for B to D_1^0 with leptons: (2.64 ± 0.79 ± 0.39) x 10^-3

Set upper limit for B to D_2^{*0} at 1.4 x 10^-3 (95% CL)

Analyzed 3.9 million Z decays with the OPAL detector

Abstract

The decay chain b -> Bbar -> D^{**0} l nu X, D^{**0} -> D^{*+} pi^-, D^{*+} -> D^0 pi^+, D^0 ->(Kpi or K3pi) is identified in a sample of 3.9 million hadronic Z decays collected with the OPAL detector at LEP. The branching ratio BR (b -> Bbar) x BR (Bbar -> D^0_1 l nu X) x BR (D^0_1 -> D^{*+} pi^-) is measured to be (2.64 +- 0.79 (stat) +- 0.39 (syst)) X 10^-3 for the J^P = 1^+ (D^0_1) state. For decays into the J^P = 2^+ (D^{*0}_2) state, an upper limit of 1.4 X 10^-3 is placed on the branching ratio at the 95% confidence level.