First Measurement of the Branching Ratio of $J/\psi\to\gamma f_{2}(1270) f_{2}(1270)$

TL;DR

This paper reports the first measurement of the decay rate of the $J/$ particle into a photon and two $f_2(1270)$ mesons, using a large dataset from the BES II detector.

Contribution

It presents the first observation and measurement of the branching ratio for the decay $J/ o \u03b3 f_2(1270) f_2(1270)$, providing new data on this decay mode.

Findings

Branching ratio measured as (9.5 ± 0.7 ± 1.6) x 10^{-4}

First observation of this decay mode

Data collected from 58 million $J/$ events

Abstract

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.