K-matrix analysis of the Kπ S-wave in the mass region 900–2100 MeV and nonet classification of scalar qq̄-states

A K-matrix re-analysis of the Kπ S-wave is performed in the mass region 900 – 2100 MeV, and solutions which describe the data well are found. The solution with two resonances in the IJP = 120+-wave has poles at (1415 ± 25) − i(165 ± 25) MeV, and (1820 ± 40) − i(125 ± 50) MeV, close to the previous result of D. Aston et al., Nucl. Phys. B 296 (1988) 493. The corresponding bare states, which are the subjects of a qq classification, are: K0bare(1220−60+50) and K0bare(1885−80+50). Within the restored bare states, a construction of the 13P0qq nonets is completed. The three resonance solutions are analysed as well, the corresponding bare states are found, and the qq̄-nonet classification is suggested. In all variants of our qq̄-classification, the resonances a0(980) and f0(980) (or their bare counterparts) are non-exotic, and an extra scalar/isoscalar state exists in the mass region 1300–1700 MeV, being a good candidate for the lightest scalar glueball.