Restrictions on the chiral angle in a soliton quark model

The authors present results of calculations for baryon properties in a quark model that incorporates new developments in lattice QCD as well as chiral invariance. The quarks are confined by a nonlinear chi field, which is motivated by averaging over the gluonic degrees of freedom in lattice QCD. Chiral invariance is achieved by meson fields ( pi , sigma ), which also lead to an interaction between the valence quarks and the Dirac sea. Due to the nonlinearity of the chi field, the authors find very special restrictions for the boundary conditions of the meson fields.