Diquarks in a chiral soliton field

In the Nambu-Jona-Lasinio model baryons are considered either as quark-diquark composites or as soliton configurations of the mesons. As a first step towards constructing a hybrid model, which possesses a dynamical interplay between both pictures, the Bethe-Salpeter equation for diquarks in the background of a soliton configuration is solved. The presence of the soliton significantly increases the binding energy of the diquark. As a consequence a unit baryon number configuration may be constructed with a mass lower than the energy of the soliton. This energy correction is shown to be of order NC0 in a large NC expansion of the classical soliton. An estimate of the influence of the diquark on the meson fields indicates a small decrease of the extension of the soliton due to diquark correlations.