Scalar mesons and the fragmented glueball

The center-of-gravity rule is tested for heavy and light-quark mesons. In the heavy-meson sector, the rule is excellently satisfied. In the light-quark sector, the rule suggests that the a0(980) could be the spin-partner of a(2)(1320), a(1)(1260), and b(1)(1235); f(0)(500) the spin-partner of f(2)(1270), f(1)(1285), and h(1)(1170); and f(0)(980) the spin-partner of f(2)'(1525), f(1)(1420), and h(1)(1415). From the decay and the production of light scalar mesons we find a consistent mixing angle theta(s) = (14 +/- 4)degrees. We conclude that f(0)(980) is likely octet-like in SU(3) with a slightly larger ss over line s (s) over bar content and f(0)(500) is SU(3) singlet-like with a larger nn over line component. The a(0)(1450), K-0*(1430), f(0)(1500) and f(0)(1370) are suggested as nonet of radial excitations. The scalar glueball is discussed as part of the wave function of scalar isoscalar mesons and not as additional intruder. It seems not to cause supernumerosity. (C) 2021 The Author. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.

Automated summary

The center-of-gravity rule is tested for heavy and light-quark mesons, showing excellent validation in the heavy-meson sector and proposing potential spin-partner relationships among light-quark mesons. The study also discusses mixing angles, SU(3) representations, and suggests nonet of radial excitations, while rejecting the scalar glueball as an additional intruder.