Nonet classification of scalar/isoscalar resonances below 1900 MeV: The existence of an extra scalar state in the region 1200-1600 MeV

A classification of the IJ(PC) = 00(++) mesons is performed on the basis of the K-matrix analysis of meson spectra in the reactions: (i) GAMS data on pi p --> pi(0) pi(0)n, eta eta n, eta eta'n [D. Aide et al., Z. Phys. C 66 (1995) 375; A.A. Kondashov et al., Proc. 27th intern. Conf. on High Energy Physics, Glasgow (1994) 1407; Yu.D. Prokoshkin et al., Physics-Doklady 342 (1995) 473; A.A. Kondashov et at, Preprint IHEP 95-137, Protvino (1995); F. Binon et al., Nuovo Cim. A 78 (1983) 313; A 80 (1984) 363]; (ii) Crystal Barrel data on <p(p)over bar> (at rest) --> pi(0) pi(0) pi(0), pi(0) pi(0) eta, pi(0) eta eta [V.V. Anisovich et al., Phys. Lett. B 323 (1994)233; C. Amsler et al., Phys. Lett. B 342 (1995) 433]; (iii) CERN-Munich data on pi p --> pi(+)pi(-)n [B. Hyams et al., Nucl. Phys. B 64 (1973) 134]; (iv) BNL data on pi N --> KKN [S.J. Lindenbaum and R.S. Longacre, Phys. Lea. B 274 (1992) 492; A. Etkin et al., Phys. Rev. D 25 (1982) 1786]. The analysis points to the existence of four comparatively narrow scalar resonances which correspond to the following poles of the scattering amplitude (in MeV): (1015 +/- 15) - i(43 +/- 8), (1300 +/- 20) - i(120 +/- 20), (1499 +/- 8) - i(65 +/- 10) and (1780 +/- 30) - i(125 +/- 70). The scattering amplitude also has a fifth pole f(0)(1530(-250)(+90)) at the complex mass (1530(-250)(+90)) - i(560 +/- 140). The masses of the K-matrix poles (bare states) are at 720 +/- 100 MeV, 1230 +/- 50 MeV, 1260 +/- 30 MeV, 1600 +/- 50 MeV and 1810 +/- 30 MeV. The quark content of the bare states is analyzed using the values of their couplings to the pi pi, (K) over bar (K) over bar, eta eta and eta eta'. It is shown that one of the bare states in the mass region 1200-1600 MeV is superfluous for the (q) over bar (q) over bar classification and should be considered as the lightest glueball.