Nonet Classification of Scalar/Isoscalar Resonances in the Mass Region below 1900 MeV: Observation of the Lightest Scalar Glueball

Abstract

We summarize the results of the investigation of the $I{J}^{PC}=00^{++}$ wave which is devoted to the search for the lightest scalar glueball. In the framework of the K-matrix formalism, the $q\bar{q}$-nonet classification of the scalar/isoscalar states is performed in the mass region below 1900 MeV basing on the following data: GAMS data for ${\pi }^{-}p\to {\pi }^0{\pi }^{0}n$, $\eta \eta n$, $\eta {\eta }^{\prime }n$; CERN-Münich data for ${\pi }^{-}p\to {\pi }^{+}{\pi }^{-}n$; Crystal Barrel data for $p\bar{p}\to {\pi }^0{\pi }^0{\pi }^0$, ${\pi }^0{\pi }^0\eta$, ${\pi }^0\eta \eta$; BNL data for $\pi \pi \to K\overline{K}$. It is shown the existence of an extra state for $q\bar{q}$ classification: this state is a good candidate for the lightest scalar glueball. Analysis of the glueball/$q\bar{q}$ mixing shows that the glueball state has mainly dispersed over three real resonances: $f_0(1300)$, $f_0(1500)$ and $f_0(1530_{-250}^{+90})$. The broad resonance with complex mass $m=1530_{-250}^{+90}-i(560\pm 140)$ MeV is descendant of the pure glueball. The restored mass of the pure glueball is equal to 1695 MeV. This value agrees well with the results of lattice gluodynamics.

Comments: LaTex, 5 pages and 7 figures. Talk given by V.V.Anisovich at LEAP96, Dinkelsbuhl, Germany