The effects of coloured glue in the QCD motivated bag of heavy quark-antiquark systems

The QCD motivated bag model is elaborated and applied to heavy quark-antiquark systems. The effect of coloured glue in the model is shown to explain the rapid cross-over of the static Q anti Q potential from the asymptotically free Coulomb regime into the linear confinement regime. The spin-dependent force between static quarks is derived in Coulomb gauge from the exchange of a confined transverse gluon. The dimensional bag parameter Λsub(B) = 235 MeV and the quark-gluon coupling constant α = 0.38 (as defined at rsub(Q anti Q) approx. 0.2 fm) are determined from a good fit of the c anti c and b anti b spectra. The fit is in serious disagreement with the widely accepted MIT parameters. As an important test of our model, we calculate the rich spectrum of (Q anti Q glue) states. In UPSILON particle spectroscopy we predict a narrow (Q anti Q glue) state with exotic quantum numbers Jsup(PC) = 1-+ below the B anti B threshold. Its experimental confirmation would be the first direct evidence for coloured glue in the hadron spectrum. (orig.)