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 IJPC = 00++ mesons is performed on the basis of the K-matrix analysis of meson spectra in the reactions: (i) GAMS data on πp → π0π0n, ηηn, ηη′n [D. Alde 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 al., 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 pp (at rest) → π0π0π0, π0π0η, π0ηη [V.V. Anisovich et al., Phys. Lett. B 323 (1994)233; C. Amsler et al., Phys. Lett. B 342 (1995) 433]; (iii) CERN-Münich data on πp → π+π−n [B. Hyams et al., Nucl. Phys. B 64 (1973) 134]; (iv) BNL data on πN → KKN [S.J. Lindenbaum and R.S. Longacre, Phys. Lett. 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 f0(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 ππ, KK, ηη and ηη′. It is shown that one of the bare states in the mass region 1200–1600 MeV is superfluous for the qq classification and should be considered as the lightest glueball.