Chiral color-dielectric model with perturbative quantum pions and gluons.

Abstract

Pionic contributions to static nucleon properties are calculated in a chiral extension of the color-dielectric model. The pion field and residual gluon field are treated perturbatively. It is shown that with a simple choice for the energy of the scalar confining field and assuming the chiral limit, the system of equations describing the bare soliton and the perturbative pion and gluon fields may be cast in a dimensionless, parameter-free form for large glueball masses. This enables a formula for the masses of the nucleon and \ensuremath{\Delta} including leading-order pionic and gluonic contributions and corrections for spurious center-of-mass motion, valid for a wide range of input parameters determining the bare-soliton solutions, to be derived. A further consequence of the scaling behavior is that pionic contributions to nucleon properties, calculated using the methods of the cloudy-bag model, are insensitive to the soliton parameters, once the size of the soliton is fixed. The model results are very similar to those of the cloudy-bag model but the predicted masses are about 20% too large, and the pionic contributions to charge radii are underestimated.