Bag Parameter Research Articles

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 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 Λ B = 235 MeV and the quark-gluon coupling constant α = 0.38 (as defined at r Q Q ≈ 0.2 fm ) determined from a good fit of the c c and b 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 Q glue) states. In υ particle spectroscopy we predict a narrow (Q Q glue) state with exotic quantum numbers J PC = 1 −+ below the B B threshold. Its experimental confirmation would be the first direct evidence for coloured glue in the hadron spectrum.