Constraints on ${\Xi }^{-}$ nuclear interactions from capture events in emulsion

Abstract

Five ${\Xi }^{-}p\to \Lambda \Lambda$ two-body capture events in ${}^{12}$C and ${}^{14}$N emulsion nuclei, in which a pair of single-$\Lambda$ hypernuclei is formed and identified by their weak decay, have been observed in $(K^{-},K^{+})$ emulsion exposures at KEK and J-PARC. Applying a ${\Xi }^{-}$-nucleus optical potential methodology to study atomic and nuclear transitions, we confirm that these capture events occur from Coulomb assisted $1p_{{\Xi }^{-}}$ nuclear states. Long-range $\Xi N$ shell-model correlations are found essential to achieve consistency between the ${}^{12}$C and ${}^{14}$N events. The resulting $\Xi$-nuclear interaction is strongly attractive, with $\Xi$ potential depth in nuclear matter $V_{\Xi }\gtrsim 20$ MeV. Implications to multi-strangeness features of dense matter are outlined.

Comments: v4: 16 pages, 2 figures, 2 tables, agrees with published PLB version