Quantum Numbers JPC Research Articles

Glueballs' masses in the bag model

The masses of low-lying glueballs with quantum numbersJPC=0++ andJPC=0−+ are calculated within the framework of the MIT bag model.

Estimate of the gluonium mass from QCD low-energy theorems

We consider the two-point function of gluonic currents with quantum numbersJPC=O++. Low-energy theorems obtained earlier starting from the QCD lagrangian allow to reconstruct, in gross features, the corresponding spectral density. The mass of the lowestO+ gluonium is estimated.

Heavy Particle Spectroscopy in the Bag Model

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 QQ̄ potential from the asymptotically free Coulomb region 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 ΛB = 235 MeV and the quark-gluon coupling constant α = 0.38 (as defined at rQQ̄ ∼ 0.2 fermi) are determined from a good fit of the cc̄ and bb̄ 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 (QQ̄ glue) states. In γ particle spectroscopy we predict a narrow (QQ̄ glue) state with exotic quantum numbers JPC = 1-+ below the BB̄ threshold. Its experimental confirmation would be the first direct evidence for coloured glue in the hadron spectrum.The spectroscopy of heavy baryons with naked charm and/or beauty is also developed. The potential energy of three heavy colour sources is determined from the bag model and the Schrödinger equation is solved by using the hyperspherical formalism.