NarrowΣ-Hypernuclear States

It is shown that the spin-isospin dependence of low-energy $\Sigma N\to \Lambda N$ conversion leads to substantial quenching of nuclear-matter estimates of the widths of some $\Sigma$-hypernuclear states produced in ($K^{-}$, $\pi$) reactions, to a level below 10 MeV. The estimated widths compare favorably with those of the $\Sigma$-hypernuclear peaks recently observed at CERN for ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$, and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$. Tentative quantum number assignments are suggested for these states.