$\mathrm{\Lambda }d$ correlations from the ${}^4$He(stopped-$K^{-}$,$d$) reaction

We have observed an intense high-energy component in an inclusive ${}^4$He(stopped $K^{-}$, $d$) spectrum. For back-to-back $\mathrm{\Lambda }d$ pairs a prominent event cluster has been found just below the $m_{{}^4\text{He}}+m_{K^{-}}-m_n$ mass threshold in the $\mathrm{\Lambda }d$ invariant mass spectrum of $\mathrm{\Lambda }dn$ events, which is evidence for a three-nucleon absorption process of $K^{-}$ in ${}^4$He. In addition, an appreciable strength is revealed below $\sim$3220 MeV/$c^2$. Well separated ${\mathrm{\Sigma }}^{0}dn$ events show a peak similar to the case of $\mathrm{\Lambda }dn$.