[en] The mixing mechanism of three axial-vector meson f₁(1285), f₁(1530) and E/f₁(1420) is discussed. The results show that the main component of E/f₁(1420) is the glueball. On this basis we calculate the ratio of the helicity amplitudes and expect an experimental test for this result

[en] Assuming the existence of quark-gluon mixing, we consider simultaneously the A (J^PC =1⁺⁺) and the B (J^PC =^1+-) families of axial mesons. We describe the existing experimental data on the decays in which these particles take part, and also obtain a large number of predictions. We show that the E(1440) and the D'(1530) contain almost equal glueball components of ∼50%. This explains many unclear features of meson spectroscopy in the mass region of 1400--1500 MeV

[en] The production of mesons by one nearly real and one quite virtual (tagged) photon continues to be an excellent tool to pick out spin-one, C=+1 particles, since these are seen in tagged but not in untagged data, in which production would have to be by two nearly real photons. The first particle seen this way, the E or f₁(1420), cannot be a quark-antiquark state and is most likely a four-quark system, or possibly a hybrid. A new spin-one, C=+1 particle has been seen at about 1.6 GeV with a 4π final state, and is also most likely another unusual meson

[en] Spin one states can be isolated in two photon fusion by use of the fact that such states are produced only if at least one of the photons is far off the mass shell. Two photon experimental data on spin one states at 1285 MeV, 1420 MeV, and candidate at 1525 MeV are discussed with special emphasis on the signal near 1525 MeV. Reasons are given for suspecting that some of these states are not conventional quark antiquark mesons. (orig.)

[en] The status of strangeonium spectroscopy is re-assessed following their recent high statistics study of K^- induced hypercharge exchange reactions. The implications of their results for the status of glueball, or otherwise exotic, candidates observed in the same decay modes but produced by different mechanisms are also discussed. 11 references, 8 figures