Measurement of {\boldmath $J/\psi\to\Xi(1530)^{-}\bar\Xi^{+}$} and evidence for the radiative decay {\boldmath $\Xi(1530)^{-}\to\gamma\Xi^-$}

TL;DR

This study measures the decay rate and angular distribution of the $J/\psi$ decay to $\\Xi(1530)^{-}\ar\Xi^{+}$, and finds evidence for the radiative decay of $\\Xi(1530)^{-}$ to $\\gamma\ ext{Xi}^{-}$, improving understanding of SU(3)-flavor violation.

Contribution

First measurement of the angular parameter for $J/\psi \to \Xi(1530)^{-} \bar\Xi^{+}$ decay and evidence for the radiative decay of $\\Xi(1530)^{-}$, with improved precision and new decay mode insights.

Findings

Branching fraction of $J/\psi \to \Xi(1530)^{-} \bar\Xi^{+}$ measured as $(3.17\pm0.02_{stat}\pm0.08_{syst})\times10^{-4}$.

First measurement of the angular parameter $\alpha$ as $-0.21\pm0.04_{stat}\pm0.06_{syst}.

Evidence for the radiative decay $\Xi(1530)^{-} \to \gamma \Xi^{-}$ with 3.9$\sigma$ significance, upper limit $\leq 3.7\%$ at 90\% CL.

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 $\mathcal{B}(\Xi(1530)^{-}\to\gamma\Xi^- )\leq3.7$\%.