Deciphering $Ξ^-$ capture events in light emulsion nuclei

Abstract

We recently showed that all five KEK and J-PARC uniquely assigned two-body $Ξ^-$+${^A}$Z$\to{_Λ^{A'}}$Z'+${_Λ^{A''}}$Z'' capture events in CNO light emulsion nuclei are consistent with Coulomb-assisted $1p_{Ξ^-}$ nuclear states in a $Ξ$-nuclear potential of nuclear-matter depth $V_Ξ\gtrsim 20$ MeV [1]. Here we argue that the recently reported $^{14}$N capture events named KINKA and IRRAWADDY are more likely $1p_{Ξ^0}$--$^{14}$C nuclear states [2] than $1s_{Ξ^-}$--$^{14}$N states, the latter assignment implying considerably smaller values of $V_Ξ$.