Towards the unified description of light and heavy hadrons in the bag model approach

Abstract

Mass spectra of ground state hadrons containing u-, d-, s-, c-quarks as well as some lightest hadrons containing b-quarks are calculated on the basis of a slightly modified bag model. The center-of-mass motion corrections are incorporated using a wavepacket projection with Gaussian parametrization of the distribution amplitude. We use running coupling constant and also allow the effective quark mass to be scale-dependent. The impact of these modifications on the hadron mass spectrum is investigated. A comparison of the predicted mass values with the experimental data demonstrates that the modified bag model is sufficiently flexible to provide a satisfactory description of light and heavy hadrons (mesons and baryons) in a single consistent framework.

Effect of the Casimir energy on the bag model phenomenology of light hadrons

“…The idea really works. The corrected values of the magnetic moments are much closer to the experimental data [7][8][9]. Still, some discrepancy remains indicating that the correction is somewhat too weak.…”

“…where E m and E e are the colour-magnetostatic and colour-electrostatic (Coulomb) pieces of the interaction energy (for more details see [9]);…”

“…Altogether, there are seven parameters -B, γ, A, R 0 , s m , δ s , and Z 0 . We will use the same prescription as in [9] for the first six of them: B, γ, A, and R 0 will be determined by fitting calculated masses of light hadrons (N, ∆, π, and the average mass of the ω-ρ system) to experimental data, s m and δ s from the fit to the masses of ϕ and Λ. There remains one more parameter Z 0 , which scales the magnitude of the Casimir energy.…”

“…Now it is almost clear how the Casimir energy may improve the magnitude of magnetic moments. The strength of the c. m. m. correction is usually derived from the fit of certain hadron masses to the experimental data [8,9]. So, if we add some positive term to the uncorrected energy, the correction would be stronger, enlarging the magnitude of the corrected magnetic moments in turn.…”

“…In previous bag model calculations [9] we have ignored the Casimir energy contribution. One reason for this was very simple -we wanted to reduce the number of free model parameters.…”