Axial Anomaly and QCD Sum Rules

O. Teryaev

Chinese Journal of Physics

34卷3S期（1996 / 06 / 01）

1074 - 1079

英文

In the framework of QCD sum rules method a constraint for the Borel transform of relevant form factors of VVA amplitude imposed by the dispersive approach to the axial anomaly is considered. The power corrections originating from the local condensates do not match this criterion. The cancellation between the contributions of the zero modes and the classical gluon fields opens the posiibility of claculating the singlet axial constant, neglecting the contribution of direct instantons. The resulting value of GA ～ 0.3 is compatible with the experimental data. The effect of dence nuclear medium leads to the decay p0→2γ. Its branching ratio to the dilepton decay width is estimated to be at the level of 10^-3.