<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">Σ</mml:mi></mml:math>Hyperons in the Nucleus

A search for $\ensuremath{\Sigma}$ hypernuclear states in $p$-shell hypernuclei has been performed with the Moby Dick spectrometer and the low energy separated beam (LESB-2) at the Brookhaven Alternating Gradient Synchrotron (BNL AGS). Unlike some previously published reports, no narrow states have been observed for targets of ${}^{6}\mathrm{Li}$ and ${}^{9}\mathrm{Be}$ in $({K}^{\ensuremath{-}},{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}})$ reactions, either for bound state or continuum regions. Together with the previously reported $J\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$, $T\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1/2$ bound state in ${}_{\ensuremath{\Sigma}}^{4}\mathrm{He}$, these results demonstrate the crucial role of isospin in $\ensuremath{\Sigma}$ hypernuclei.