Eur Phys J C (2004) 33: s578-s582
https://doi.org/10.1140/epjcd/s2004-03-1687-9

PS05 Hadronic Physics

Recent charmonium results from BES

¹ Institute of High Energy Physics, Beijing, China
² Dept. of Physics and Astronomy, University of Hawaii, Honolulu, HI 96822, USA

Received: 20 October 2003
Accepted: 9 January 2004
Published online: 19 February 2004

Abstract

Using 58 million J/ψ decays, we have investigated the invariant mass spectrum in the radiative decay and observe a prominent structure with mass near 2m _p . Fitting with an S-wave Breit-Wigner, we obtain a peak mass of M= 1859⁺³ _–10(stat)⁺⁵ _–25(sys) MeV/c². J/ψ → γ η _c decays from the same sample are used to determine the mass, width, and hadronic branching ratios of the η _c . From a sample of 14 million ψ(2S) events, the first observation of χ _cJ (J=0,1,2) decays to is made, and branching ratios are determined, which are larger than expected from the Color Octet Model. Branching ratios of K _s ⁰ K _L ⁰ in both ψ(2S) and J/ψ decays are measured, and a more than four sigma deviation from the pQCD-predicted ”12% rule” is observed. In ψ(3770) decays, evidence for the non- decay to π ⁺ π ^– J/ψ is observed.

PACS: 13.20.Gd Decays of J/psi, Upsilon, and other quarkonia