The Chiral Soliton of the Nambu Jona-Lasinio Model with Vector and Axial Vector Mesons

Abstract

The self-consistent chiral soliton of the Nambu--Jona-Lasinio model including the $\omega,\rho$ and $a_1$ (axial-) vector meson fields besides the chiral angle is investigated. The resulting energy spectrum of the one particle Dirac Hamiltonian is strongly distorted leading to a polarized Dirac sea which carries the complete baryon number. This supports Witten's conjecture that baryons can be described as topological solitons. The exploration of the isoscalar mean squared radius of the nucleon exhibits that the repulsive character of the isoscalar vector field $\omega$ as well as the attractive features of the (axial-) vector mesons $\rho$ and $a_1$ are reproduced in the Nambu--Jona-Lasinio model. The axial charge of the nucleon $g_A$ comes out far too small. This can be understood as an artifact of the proper time regularization prescription.