Measurement of the inclusive semileptonic branching fraction of B mesons and |Vcb|

TL;DR

This paper measures the inclusive semileptonic branching fraction of B mesons and extracts the CKM matrix element |Vcb| using electron spectra from B decays, with minimal model dependence, based on Belle data.

Contribution

First precise measurement of B meson semileptonic branching fraction and |Vcb| using high-momentum lepton tagging and minimal model assumptions.

Findings

Branching fraction: (10.90 ± 0.12 ± 0.49)%

|V_{cb}|: 0.0408 ± 0.0010 (exp) ± 0.0025 (th)

Minimal model dependence in measurement

Abstract

We present a measurement of the electron spectrum from inclusive semileptonic {\it B} decay, using 5.1 fb$^{-1}$ of $\Upsilon(4S)$ data collected with the Belle detector. A high-momentum lepton tag was used to separate the semileptonic {\it B} decay electrons from secondary decay electrons. We obtained the branching fraction, ${\cal B}(B\to X e^+ \nu) = (10.90 \pm 0.12 \pm 0.49)%$, with minimal model dependence. From this measurement, we derive a value for the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}| = 0.0408 \pm 0.0010 {\rm (exp)} \pm 0.0025{\rm (th)}$.