Hadron masses in cavity quantum chromodynamics to order $\alpha_{\rm s}^2$

Abstract

The non-divergent diagrams describing two-gluon exchange and annihilation between quarks and antiquarks are calculated in the Feynman gauge, based on quantum chromodynamics in a spherical cavity. Using the experimental N , ∆, Ω, and ρ masses to fit the free parameters of the M.I.T. bag model, the predicted states agree very well with the observed low-lying hadrons. As expected, the two-gluon annihilation graphs lift the degeneracy of the π and η, while the ρ and ω remain degenerate. Diagonalizing the η − η ′ subspace Hamiltonian yields a very good value for the mass of the η meson.

Spin structure of the nucleon: QCD evolution, lattice results and models

“…It represents a free parameter chosen in such a way that the model reproduces the light hadron spectrum [48]. The values used in the literature vary between αs = 1 [49] and αs = 2.2 [50]. We use these two values as options in the results shown later in Table 3 and 4.…”