K-MATRIX ANALYSIS OF THE K-PI S-WAVE IN THE MASS REGION 900-2100 MEV AND NONET CLASSIFICATION OF SCALAR Q(Q)OVER-BAR-STATES

A K-matrix re-analysis of the K pi S-wave is performed in the mass reg ion 900 - 2100 MeV, and solutions which describe the data well are fou nd. The solution with two resonances in the (IJ(P) = 1/2 0(+))-wave ha s poles at (1415 +/- 25) - i(165 +/- 25) MeV and (1820 +/- 40)-i(125 /- 50) MeV, close to the previous result of D. Aston ct al., Nucl. Phy s. B 296 (1988) 493. The corresponding bare states, which are the subj ects of a q (q) over bar classification, are: K-0(bare)(1220(-60)(+50) ) and K-0(bare)(1885(-80)(+50)). Within the restored bare states, a co nstruction of the 1(3)P(0) q (q) over bar and 2(3)P(0) q (q) over bar nonets is completed. The three resonance solutions are analysed as wel l, the corresponding bare states are found, and the q (q) over bar-non et classification is suggested. In all variants of our q (q) over bar- classification, the resonances a(0)(980) and f(0)(980) (or their bare counterparts) are non-exotic, and an extra scalar/isoscalar state exis ts in the mass region 1300-1700 MeV, being a good candidate for the li ghtest scalar glueball. (C) 1997 Elsevier Science B.V.