A review of central production experiments at the CERN Omega   spectrometer
  The non-Abelian nature of QCD suggests that particles that have a gluon constituent, such as glueballs or hybrids, should exist. This paper presents a study of central meson production in the fixed target experiments WA76, WA91 and WA102 at the CERN Omega spectrometer at centre-of-mass energies of $\sqrt{s} = 12.7$, 23.8 and 29~GeV. A study of the resonance production cross section as a function of $\sqrt{s}$ shows which states are compatible with being produced by Double Pomeron Exchange (DPE). In these DPE processes, the difference in the transverse momentum between the exchange particles ($dP_T)$ can be used to select out known $q\overline q$ states from non-$q \overline q$ candidates. The distribution of the azimuthal angle ($\phi$) between the two exchange particles suggests that the Pomeron transforms like a non-conserved vector current. Finally there is evidence from an analysis of the the decay modes of the scalar states observed, that the lightest scalar glueball manifests itself through the mixing with nearby $q\overline q$ states. 
Andrew Kirk
hep-ex hep-ph