标题： $J/ψ\toγf_{2}(1270) f_{2}(1270)$的分支比首次测量 显示英文标题

标题： First Measurement of the Branching Ratio of $J/ψ\toγf_{2}(1270) f_{2}(1270)$

摘要： 使用在北京正负电子对撞机上用BES II探测器采集的5800万$J/\psi$事例，首次观察到一种新的衰变模式$J/\psi\to\gamma f_{2}(1270) f_{2}(1270) \to \gamma \pi^+\pi^-\pi^+\pi^-$。分支比被确定为$Br(J/\psi\to\gamma f_{2}(1270) f_{2}(1270))=(9.5\pm0.7\pm1.6)\times 10^{-4}$，其中给出的误差分别为统计误差和系统误差。 显示英文摘要

摘要： Using 58 million $J/\psi$ events taken with the BES II detector at the Beijing Electron Positron Collider, a new decay mode $J/\psi\to\gamma f_{2}(1270) f_{2}(1270) \to \gamma \pi^+\pi^-\pi^+\pi^-$ is observed for the first time. The branching ratio is determined to be $Br(J/\psi\to\gamma f_{2}(1270) f_{2}(1270))=(9.5\pm0.7\pm1.6)\times 10^{-4}$, where the quoted errors are statistical and systematic, respectively.