Mathematical aspects of U_A(1) breaking in effective multi-quark interactions

Abstract:
The six-quark instanton induced 't Hooft interaction, which breaks the unwanted U_A(1) symmetry of QCD is also a source of perturbative corrections. A detailed quantitative calculation is carried out using the functional integral method to bosonize the effective fermion interactions of the Nambu-Jona-Lasinio type. The resulting corrections may be important for the low-energy spectrum and dynamics of the scalar and pseudoscalar nonets.

1. A.A. Osipov, B. Hiller, Path integral bosonization of the 't Hooft determinant: quasiclassical corrections,  Eur. Phys. J. C35 (2004), 223-241; hep-th/0307035.
2. A.A. Osipov, H. Hansen, B. Hiller, Long distance expansion for the NJL model with SU(3) and U_A(1) breaking,  Nucl. Phys. A745 (2004), 81-103; hep-ph/0406112 .