Newly observed $a_0(1817)$ as the scaling point of constructing the scalar meson spectroscopy

Abstract

Stimulated by the newly observed a 0 (1817) by the BESIII Collaboration, we find a perfect Regge trajectory composed of the a 0 (980), a 0 (1450), and a 0 (1817), which leads us to categorize the a 0 (980), a 0 (1450), and a 0 (1817) into the isovector scalar meson family. This scenario is supported by their two-body Okubo-Zweig-Iizuka allowed strong decay behaviors. In this scheme, we also predict the third radial excitation of the a 0 (980), which is denoted as the a 0 (2115), accessible at future experiment as a direct test of this assignment. We find another Regge trajectory which contains three isoscalar scalar states f 0 (980), X(1812), and f 0 (2100). We investigate their two-body Okubo-Zweig-Iizuka allowed strong decay patterns, which are roughly consistent with the experimental data. The f 0 (980), X(1812), and f 0 (2100) can be well grouped into the isoscalar scalar meson family. We want to emphasize that these two Regge trajectories have a similar slope. In summary, the present work provides a scheme of constructing the scalar meson family based on these reported scalar states. The possibility of the f 0 (1710) as the candidate of the scalar glueball cannot be excluded by the observation of the a 0 (1817) since the a 0 (1817) is more suitable as the isovector partner of the X(1812).