Axial anomaly and low energy tests for instanton vacuum models in QCD

We propose to test instanton models of QCD – in particular the single instanton approximation and the Diakonov and Petrov model – against some exact relations inferred from QCD + QED axial anomaly. One of these relations, in chiral limit, is satisfied by the latter model, but not by the former one. More refined tests, obtained beyond the chiral limit, are not fulfilled by the Diakonov and Petrov model.