Mass Spectrum of a Meson Nonet is Linear
  It is argued that the mass spectrum of a meson nonet is linear, consistent with the standard Gell-Mann--Okubo mass formula and leading to an extra Gell-Mann--Okubo mass relation for the masses of the isoscalar states. This relation is shown to hold with an accuracy of up to $\sim $3\% for all well-established nonets. It also suggests a new $q\bar{q}$ assignment for the scalar meson nonet. 
L. Burakovsky and L.P. Horwitz