Mixing mechanism for the $J^{P}=0^{+}$ mesons

Abstract

There are three scalar nonets in the Particle Data Group (PDG), one of which includes [$a_0(980), K_0^*(700)$], another includes [$a_0(1450), K_0^*(1430)$], and the third includes [$a_0(1710), K_0^*(1950)$]. Motivated by Ref.[1], we examine an alternative mixing mechanism that could potentially explain the small mass difference between the $a_0 (1450)$ and $K_0^* (1430)$. According to the tetraquark mixing model, two types, distinguished by their color-spin structures, are necessary to describe the tetraquark structure of the two nonets containing [$a_0(980), K_0^*(700)$] and [$a_0(1450), K_0^*(1430)$]. Considering the color-spin structures, we argue that the mixing mechanism generating $a_0(1450)$ and $K_0^* (1430)$ on the one hand, and $a_0(1710)$ and $K_0^* (1950)$ on the other hand might be relevant for resolving the small mass difference. We also discuss the limitations of other mixing mechanisms that generate the two nonets involving [$a_0(980),K_0^*(700)$] and [$a_0(1450)$, $K_0^* (1430)$] or [$a_0(980),K_0^*(700)$] and [$a_0(1710)$, $K_0^* (1950)$]