Axial Anomaly and Transition Formfactors

TL;DR

This paper investigates photon-meson transition form factors using dispersive methods related to the axial anomaly, showing that small corrections to the continuum can significantly impact the pion form factor, with less effect on eta mesons.

Contribution

It introduces a dispersive approach to axial anomaly that does not rely on factorization, providing new insights into corrections affecting meson form factors based on recent experimental data.

Findings

Small corrections to the continuum significantly affect the pion form factor.

The correction effects are less pronounced for the eta meson.

The approach aligns with recent BaBar data.

Abstract

We study photon-meson transition formfactors of light mesons in the kinematics, where one photon is real and other is virtual. Dispersive approach to axial anomaly leads to the anomaly sum rule. The absence of corrections to it allows us to get the relation between possible corrections to continuum and to lower states within QCD method which does not rely on factorization hypothesis. We show, relying on the recent data of the BaBar Collaboration, that the relative correction to continuum is quite small, and small correction to continuum can dramatically change the pion formfactor. The same effect for {\eta} meson is shown to be less pronounced.