Resonances around 2 GeV: qq and glueballs Original Research Article

Crystal Barrel data reveal systematics of View the MathML source resonances up to 2410 MeV. In particular, all expected JPC = 2++, I = 0, View the MathML source states may be identified in this range of masses M. For most JPC, observed resonances lie close to straight line trajectories of M2 v. radial quantum number, all having a uniform slope of 1.1 ± 0.03 GeV2 per excitation. Tensor and spin-orbit splitting is small. Resonances with L = J + 1 lie ∼ 100 MeV higher in mass than those with L = J − 1. Several states remain which do not fit naturally into this scheme, notably f0(1500), f0(2105), a broad 2+ state at 1980±50 MeV and a broad 0− resonance at 2190±40 MeV. Their mass ratios agree within small errors (3–14%) with Lattice QCD calculations of Morningstar and Peardon for glueballs. The f0(2105) appears strongly in the ηη channel, but not in ππ. This indicates exotic character. If interpreted in terms of a mixed state View the MathML source, then f = (65 ± 6)°.