Unsubtracted Dispersion Relation and the Anomalous Term
Hiroyuki Kikugawa · Progress of Theoretical Physics · 1972
We investigate the axial vector (pseudoscalar) current-two-photon triangle graph by means of unsubtracted dispersion relations. The anomalous term appears in agreement with the previous Feynman-Dyson calculations using regulators and is found to be present because of the fact that the axial vector current-two-photon form factor G(s) does not satisfy the superconvergence relation \int∞4m2 Im G (s) ds = 0. We also discuss the kinematical difference between the matrix element of the axial vector current and that of the divergence of the axial vector current.