Binding of hypernuclei in the latest quark-meson coupling model

Abstract

The most recent development of the quark-meson coupling (QMC) model, in which the effect of the mean scalar field in-medium on the hyperfine interaction is also included self-consistently, is used to compute the properties of finite hypernuclei. The calculations for $\Lambda$ and $\Xi$ hypernuclei are of comparable quality to earlier QMC results without the additional parameter needed there. Even more significantly, the additional repulsion associated with the increased hyperfine interaction in-medium completely changes the predictions for $\Sigma$ hypernuclei. Whereas in the earlier work they were bound by an amount similar to $\Lambda$ hypernuclei, here they are unbound, in qualitative agreement with the experimental absence of such states. The equivalent non-relativistic potential felt by the $\Sigma$ is repulsive inside the nuclear interior and weakly attractive in the nuclear surface, as suggested by the analysis of $\Sigma$-atoms.