Measurement of the $B\to D\ell\nu$ Branching Fractions and Form Factor

TL;DR

This study measures the branching fractions and form factor of B-meson decays to D mesons with leptons, providing precise decay rates and implications for the CKM matrix element |V_{cb}| using data from the CLEO detector.

Contribution

First measurement of B to D semileptonic decay rates and form factors using CLEO data, with detailed analysis of decay properties and implications for |V_{cb}|.

Findings

Decay rate Γ(B→Dℓν) = (14.1 ± 1.0 ± 1.2) ns⁻¹

Branching fractions: (2.32 ± 0.17 ± 0.20)% for B⁻→D⁰ℓν and (2.20 ± 0.16 ± 0.19)% for B̅⁰→D⁺ℓν

Insights into the B→Dℓν form factor and |V_{cb}|

Abstract

Using a sample of 3.3 million B-meson decays collected with the CLEO detector at the Cornell Electron Storage Ring, we have studied $B^- \to D^0 \ell\nu$ and $\bar{B}^0 \to D^+ \ell\nu$ decays, where $\ell$ can be either an electron or muon. We distinguish $B \to D \ell\nu$ from other B semileptonic decays by examining the net momentum and energy of the particles recoiling against the D-lepton pairs. We find the decay rate $\Gamma(B \to D\ell\nu)$ = (14.1 +- 1.0 +- 1.2) ns-1 and derive branching fractions for $B^- \to D^0 \ell\nu$ and $\bar{B^0} \to D^+ \ell\nu$ of (2.32 +- 0.17 +- 0.20)% and 2.20 +- 0.16 +- 0.19)% respectively, where the uncertainties are statistical and systematic. We also investigate the $B \to D \ell\nu$ form factor and the implication of the result for $|V_{cb}|$.