BES Results on Charmonium Decays and Transitions

TL;DR

This paper reports precise measurements of various charmonium decay branching fractions and observes new decay modes involving scalar and vector meson pairs, based on large BESII datasets.

Contribution

It provides improved branching fraction measurements and first observations of specific meson pair productions in $ ext{chi}_{cJ}$ decays.

Findings

Improved measurements of $J/\psi$ and $\psi(2S)$ decay branching fractions.

First observation of $f_0(980)f_0(980)$ production in $\chi_{c0}$ decays.

First observation of $K^*(892)^0\bar K^*(892)^0$ production in $\chi_{cJ}$ decays.

Abstract

Results are reported based on samples of 58 million $J/\psi$ and 14 million $\psi(2S)$ decays obtained by the BESII experiment. Improved branching fraction measurements are determined, including branching fractions for $J/\psi\to\pi^+\pi^-\pi^0$, $\psi(2S)\to \pi^0 J/\psi$, $\eta J/\psi$, $\pi^0 \pi^0 J/\psi$, anything $J/\psi$, and $\psi(2S)\to\gamma\chi_{c1},\gamma\chi_{c2}\to\gamma\gamma\jpsi$. Using 14 million $\psi(2S)$ events, $f_0(980)f_0(980)$ production in $\chi_{c0}$ decays and $K^*(892)^0\bar K^*(892)^0$ production in $\chi_{cJ}~(J=0,1,2)$ decays are observed for the first time, and branching ratios are determined.