Measurement of the branching fraction and decay asymmetry of $\hat{I}›\to n{\hat{I}}^3$

Abstract

The radiative hyperon decay $\hat{I}›\to n{\hat{I}}^3$ is studied using $(10087\pm 44)\times 10^6$ $J/\ddot{I}ˆ$ events collected with the BESIII detector operating at BEPCII. The absolute branching fraction of the decay $\hat{I}›\to n{\hat{I}}^3$ is determined with a significance of 5.6$\ddot{I}ƒ$ to be $[0.832\pm 0.038(stat.)\pm 0.054(syst.)]\times 10^{-3}$, which lies significantly below the current PDG value. By analyzing the joint angular distribution of the decay products, the first determination of the decay asymmetry $\hat{I}{\pm }_{\hat{I}}^3$ is reported with a value of $-0.16\pm 0.10(stat.)\pm 0.05(syst.)$.