Abstract
The SU(3)-flavor violating decay $J/\psi\to\Xi(1530)^{-}\bar\Xi^{+}+c.c.$ is studied using $(1310.6\pm7.0)\times 10^{6} ~J/\psi$ events collected with the BESIII detector at BEPCII and the branching fraction is measured to be ${\cal{B}}(J/\psi\to\Xi(1530)^{-}\bar\Xi^{+}+c.c.)=(3.17\pm0.02_{\rm stat.}\pm0.08_{\rm syst.})\times10^{-4}$. This is consistent with previous measurements with an improved precision. The angular parameter for this decay is measured for the first time and is found to be $\alpha=-0.21\pm0.04_{\rm stat.}\pm0.06_{\rm syst.}$. In addition, we report evidence for the radiative decay $\Xi(1530)^{-}\to\gamma\Xi^- $ with a significance of 3.9$\sigma$, including the systematic uncertainties. The 90\% confidence level upper limit on the branching fraction is determined to be $\mathcal{B}(\Xi(1530)^{-}\to\gamma\Xi^- )\leq3.7$\%.
Highlights
The Ξ and Ξð1530Þ hyperons are regarded as SU(3) octetand decuplet
The SU(3)-flavor violating decay J=ψ → Ξð1530Þ−Ξþ þ c:c: is studied using ð1310.6 Æ 7.0Þ × 106 J=ψ events collected with the BESIII detector at BEPCII, and the branching fraction is measured to be BðJ=ψ → Ξð1530Þ−Ξþ þ c:c:Þ 1⁄4 ð3.17 Æ 0.02stat Æ 0.08systÞ × 10−4
The decays are simulated by EVTGEN [30] with the known branching fractions taken from the Particle Data Group (PDG) [9], while the remaining unmeasured decay modes are generated with LUNDCHARM [31]
Summary
The Ξ and Ξð1530Þ hyperons are regarded as SU(3) octet There are no theoretical predictions or experimental data available on the angular distributions for SU(3)-flavor violating J=ψ decays. Only an upper limit for BðΞð1530Þ− → γΞ−Þ < 4% is reported at the 90% C.L. in 1975 [23] In this analysis, based on ð1310.6 Æ 7.0Þ × 106 J=ψ events [12] collected with the BEijing Spectrometer III (BESIII) at the Beijing Electron-Positron Collider (BEPCII), we measure the branching fraction of J=ψ → Ξð1530Þ−Ξþ with an improved precision and determine the angular distribution parameter for the first time. We report evidence for the Ξð1530Þ− → γΞ− decay with a 3.9σ significance based on the J=ψ → Ξð1530Þ−Ξþ process, and the corresponding 90% C.L. upper limit on the branching fraction is given
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