Binding of hypernuclei in the latest quark-meson coupling model

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 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. (C) 2008 Elsevier B.V. All rights reserved.