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

Abstract

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 πp → π 0 π 0 n, 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 p p ( at rest) → π 0π 0π 0, π 0π 0η, π 0ηη [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 → K KN [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 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 ππ, K K , ηη and ηη′. It is shown that one of the bare states in the mass region 1200–1600 MeV is superfluous for the q q classification and should be considered as the lightest glueball.