Scalar isoscalar mesons and the scalar glueball from radiative $J/\psi$ decays

Abstract

A coupled-channel analysis of BESIII data on radiative $J/\psi$ decays into $\pi \pi$, $K\bar{K}$, $\eta \eta$ and $\omega \varphi$ has been performed. The partial-wave amplitude is constrained by a large number of further data. The analysis finds ten isoscalar scalar mesons. Their masses, widths and decay modes are determined. The scalar mesons are interpreted as mainly SU(3)-singlet and mainly octet states. Octet isoscalar scalar states are observed with significant yields only in the 1500-2100\,MeV mass region. Singlet scalar mesons are produced over a wide mass range but their yield peaks in the same mass region. The peak is interpreted as scalar glueball. Its mass and width are determined to $M=1865$\er25${}_{-30}^{+10}$ {\rm MeV} and $\Gamma =370$\er$50_{-20}^{+30}$ {\rm MeV}, its yield in radiative $J/\psi$ decays to ($5.8\pm 1.0)10^{-3}$.

Comments: 11 pages, 4 figures