Description of the recently observed hypernucleus $^{15}{\!\!\!_{Ξ^-}}$C within a quark-meson coupling model

Abstract

We investigate within a quark-meson coupling (QMC) model, the structure of the bound $Ξ^-$ hypernucleus $^{15}{\!\!\!_{Ξ^-}}$C ($^{14}$N + $Ξ^-$), which has been observed in a recent analysis of the KEK-E373 experiment. In the QMC model, light quarks in nonoverlapping nucleon and $Ξ^-$ bags interact self-consistently with isoscalar-scalar ($σ$), isoscalar-vector ($ω$), and isovector-vector ($ρ$) mesons in the mean field approximation. The parameters of the model (quark-meson coupling constants and masses) are mostly fixed from the nuclear matter saturation properties. The QMC model closely reproduces the separation energies of the two $Ξ^-$ hyperon states in $^{15}{\!\!\!_{Ξ^-}}$C reported in the KEK-E373 analysis, and identifies their quantum numbers. We also make predictions for the cross sections for the production of the $^{15}{\!\!\!_{Ξ^-}}$C hypernuclear specta in the ($K^-, K^+$) reaction on a $^{15}$O target within a covariant effective Lagrangian model using the $Ξ^-$ bound state spinors obtained within the same QMC model.

17 Pages, 4 figures