Axial anomaly as a collective effect of meson spectrum

TL;DR

This paper investigates how the axial anomaly manifests as a collective effect of the meson spectrum in light meson transition form factors, using a dispersive QCD approach and recent experimental data.

Contribution

It introduces a dispersive method to relate axial anomaly corrections to meson spectrum contributions without relying on factorization.

Findings

Small corrections to the continuum are consistent with recent BaBar data.

Minor continuum corrections can significantly impact the pion form factor.

The approach links axial anomaly effects directly to meson spectrum properties.

Abstract

We study the transition form factors of the light mesons in the kinematics, where one photon is real and other is virtual. Using the dispersive approach to axial anomaly we show that the axial anomaly in this case reveals itself as a collective effect of meson spectrum. This 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 BaBar Collaboration, that the relative correction to continuum is quite small, and small correction to continuum can dramatically change the pion form factor.