Observation of $Y(3940)\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\omega}$ in $B\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\omega}K$ at BABAR

Observation of $Y (3940) \to J / ψ ω$ in $B \to J / ψ ω K$ at BABAR

B. Aubert et al. (BABAR Collaboration)

Phys. Rev. Lett. 101, 082001 – Published 20 August 2008

Abstract

We present a study of the decays $B^{0, +} \to J / ψ ω K^{0, +}$ using $383 \times 10^{6}$ $B \bar{B}$ events obtained with the BABAR detector at PEP-II. We observe $Y (3940) \to J / ψ ω$ , with mass ${3914.6}_{- 3.4}^{+ 3.8} (stat) \pm 2.0 (syst) MeV / c^{2}$ , and width $34_{- 8}^{+ 12} (stat) \pm 5 (syst) MeV$ . The ratio of $B^{0}$ and $B^{+}$ decay to $Y K$ is ${0.27}_{- 0.23}^{+ 0.28} (stat)_{- 0.01}^{+ 0.04} (syst)$ , and the relevant $B^{0}$ and $B^{+}$ branching fractions are reported.