Observation of a Be double-Lambda hypernucleus in the J-PARC E07 experiment. (22nd February 2019) - Ekawa, H
Abstract: A double-$\Lambda$ hypernucleus, ${}_{\Lambda\Lambda}\mathrm{Be}$, was observed by the J-PARC E07 Collaboration in nuclear emulsions tagged by the ($K^{-}, K^{+}$ ) reaction. This event was interpreted as the production and decay of $ {}_{\Lambda\Lambda}^{\;10}\mathrm{Be}$, ${}_{\Lambda\Lambda}^{\;11}\mathrm{Be}$, or ${}_{\Lambda\Lambda}^{\;12}\mathrm{Be}^{*}$ via $\Xi^{-}$ capture in ${}^{16}\mathrm{O}$ . By assuming capture in the atomic 3D state, the binding energies of two $\Lambda$ hyperons ($B_{\Lambda\Lambda}$ ) of these double-$\Lambda$ 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, ${}_{\Lambda\Lambda}^{\;11}\mathrm{Be}$ is the most likely explanation for the observed event.