Comment on “Understanding the scalar meson $q\bar{q}$ nonet”

Abstract.

It is shown that the incomplete scalar meson nonets found by Törnqvist [1] and Törnqvist & Roos [2], employing a new version of the Helsinki unitarised quark model, should in fact be complete, including an as yet unconfirmed light $K_0^*$ below 1 GeV (old $\kappa$) and the established $f_0$(1500). A detailed comparison is presented with the predictions of the Nijmegen unitarised meson model, in which two complete scalar nonets show up below 1.5 GeV [3]. The reason for the flavour-nonet breaking found in [1,2] we argue to originate in the use of coupling constants for the three-meson vertex which are not independent of flavour. Also some statements made in [1] are critically reviewed.