Limit on the <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>b</mi><mo>→</mo><mi>u</mi></math></span> Coupling from Semileptonic <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math></span> Decay

doi:10.1103/PhysRevLett.52.1084

Limit on the $b \to u$ Coupling from Semileptonic $B$ Decay

A. Chen et al.

Phys. Rev. Lett. 52, 1084 – Published 26 March 1984

Abstract

We have used the momentum spectrum of leptons produced in semileptonic $B$ -meson decays to set a 90%-confidence-level upper limit on $\frac{Γ (b \to ul ν)}{Γ (b \to cl ν)}$ of 4%. We also measure the semileptonic branching fractions of the $B$ meson to be (12.0±0.7±0.5)% for electrons and (10.8±0.6±1.0)% for muons.