Observation of a Charmoniumlike State Produced in Association with a $J/\ensuremath{\psi}$ in ${e}^{+}{e}^{\ensuremath{-}}$ Annihilation at $\sqrt{s}\ensuremath{\approx}10.6\text{ }\text{ }\mathrm{GeV}$

Observation of a Charmoniumlike State Produced in Association with a $J / ψ$ in $e^{+} e^{-}$ Annihilation at $\sqrt{s} \approx 10.6 GeV$

K. Abe et al. (Belle Collaboration)

Phys. Rev. Lett. 98, 082001 – Published 20 February 2007

Abstract

We report the first observation of a charmoniumlike state recoiling from the $J / ψ$ in the inclusive process $e^{+} e^{-} \to J / ψ + anything$ at a mass of $(3.943 \pm 0.006 \pm 0.006) GeV / c^{2}$ . We also observe the decay of this state into $D^{*} \bar{D}$ and determine its intrinsic width to be less than $52 MeV / c^{2}$ at the 90% C.L. These results are obtained from a $357 {fb}^{- 1}$ data sample collected with the Belle detector near the $Υ (4 S)$ resonance, at the KEKB asymmetric-energy $e^{+} e^{-}$ collider.