Measurement of the branching fractions for J/psi ---> gamma pi0, gamma eta and gamma eta-prime

F. De Mori, S.S. Fang, H. X. Yang, M. G. Zhao, L. Zhou, Fu Ma, Y.S. Dai, Z. P. Zhang, F. Liu, H. L.

Abstract

The decay modes $\jpsi\ar\gamma\pi^0, \gamma\eta$ and $\gamma\etap$ are analyzed using a data sample of 58 million $\jpsi$ decays collected with the BESII detector at BEPC. The branching fractions are determined to be: $Br(\jpsi\ar\gamma\pi^0)=(3.13^{+0.65}_{-0.44})\times10^{-5}$, $Br(\jpsi\ar\gamma\eta)=(11.23\pm0.89)\times10^{-4}$, and $Br(\jpsi\ar\gamma\etap)=(5.55\pm0.44)\times10^{-3}$, where the errors are combined statistical and systematic errors. The ratio of partial widths $\Gamma(\jpsi\ar\gamma\etap)/\Gamma(\jpsi\ar\gamma\eta)$ is measured to be $4.94\pm0.40$, and the singlet-octet pseudoscalar mixing angle of $\eta-\etap$ system is determined to be $\theta_{P}=(-22.08\pm0.81)^{\circ}$.

Locations

• arXiv (Cornell University) - View - PDF