Momentum projection and relativistic boost of solitons. II. Nucleon and meson properties

In a previous paper we presented a method for calculating center-of-mass corrections to hadron properties in soliton models. Here we apply this method to the soliton bag model. We construct quantum bag solutions of quarks interacting with a scalar σ field and color gauge fields in the one-gluon-exchange approximation. The σ part of Hilbert space is described by a coherent or general one-mode state. The Lorentz invariance of the theory requires the construction of momentum eigenstates with energies obeying the Einstein relation. Variation after projection onto zero momentum gives approximate mass eigenstates which are boosted relativistically onto states of nonzero momentum. This avoids the well-known Peierls-Yoccoz problem. Electromagnetic moments are evaluated. We obtain expressions for charge rms radii and nucleon magnetic moments, including recoil corrections. Other observables, which require the use of zero-momentum states are nucleon and meson masses, the axial-vector coupling constant $g_A$(0) , and the pion decay constant $f_{\pi }$. We determine the soliton bag parameters by a least-squares fit to the observed nucleon and pion masses, the charge rms radius and the magnetic moment of the proton and $g_A$; the other observables are then ‘‘predicted.’’