Contact Interaction Model for the ? And?0 Mesons in a Schwinger-Dyson-Bethe-Salpeter Approach to QCD: Masses, Decay Widths, and Transition Form Factors

We construct a contact interaction model for the & eta; and & eta;0 mesons in the SDE-BSE approach to QCD and compute several static properties of these mesons and their transition form factors. We find that this model gives an excellent description of the & eta; and & eta;0 static properties, namely, their masses, decay width, and decay constants. However, a contact interaction disagrees with experimental data for Q2 greater than 2 GeV2, and produces transition form factors in conflict with perturbative QCD prediction. This is not surprising and the reasons for this are explained.