Mass splitting of the pseudoscalar and vector mesons induced by the homogeneous vacuum gluon field

Masses of the pseudoscalar and vector mesons are calculated within the generalized Nambu-Jona-Lasinio model taking into account homogeneous vacuum gluon field. This vacuum provides an analytical quark confinement. Colorless modes are determined by the confined gluons and are described by the nonlocal quark currents with appropriate radial and angular quantum numbers. An interaction of the quark spin with the vacuum gluon field arises naturally within the model under consideration. It is shown that this spin-field interaction leads to mass splitting between vector and pseudoscalar mesons with identical quark structure (ρ-π, K-K* and so on). This allows to use the four-fermion coupling constant being common for both nonets. (orig.)