Deciphering $\Xi^-$ capture events in light emulsion nuclei

Abstract

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