Observation of a Be double-Lambda hypernucleus in the J-PARC E07 experiment

Abstract

A double-$\hat{I}›$ hypernucleus, ${}_{\hat{I}›\hat{I}›}\mathrm{Be}$, was observed by the J-PARC E07 collaboration in nuclear emulsions tagged by the $(K^{-},K^{+})$ reaction. This event was interpreted as a production and decay of ${}_{\hat{I}›\hat{I}›}^{10}\mathrm{Be}$, ${}_{\hat{I}›\hat{I}›}^{11}\mathrm{Be}$, or ${}_{\hat{I}›\hat{I}›}^{12}{\mathrm{Be}}^{\ast }$ via $\hat{I}{ž}^{-}$ capture in ${}^{16}\mathrm{O}$. By assuming the capture in the atomic 3D state, the binding energy of two $\hat{I}›$ hyperons($B_{\hat{I}›\hat{I}›}$) of these double-$\hat{I}›$ hypernuclei are obtained to be $15.05\pm 0.11\mathrm{MeV}$, $19.07\pm 0.11\mathrm{MeV}$, and $13.68\pm 0.11\mathrm{MeV}$, respectively. Based on the kinematic fitting, ${}_{\hat{I}›\hat{I}›}^{11}\mathrm{Be}$ is the most likely explanation for the observed event.

11 pages, 3 figures