Observation of Y(3940) -> J/psi omega in B -> J/psi omega K at BABAR

Abstract

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

Published: Phys. Rev. Lett. 101, 082001 (2008)