Matching lightcone- and anomaly-sum-rule predictions for the pion-photon transition form factor

TL;DR

This paper compares Light Cone Sum Rules and Anomaly Sum Rules to analyze the pion-photon transition form factor, establishing the applicability limits of LCSR at low momenta and exploring the momentum dependence of the ASR threshold.

Contribution

It introduces a method to compare LCSR and ASR predictions for the pion-photon transition form factor and investigates their consistency across different momentum ranges.

Findings

LCSR applicability limit at low momenta is identified.

ASR threshold approaches a constant at high Q2.

Comparison enhances understanding of sum rule methods for form factors.

Abstract

The pion-photon transition form factor is studied by employing two types of Sum Rules: Light Cone Sum Rules (LCSR) and Anomaly Sum Rules (ASR). By comparing the predictions for the pion-photon transition form factor, obtained from these two approaches, the applicability limit of the LCSRs at low momenta is determined. Reciprocally, the ASR threshold dependence on the momentum was extracted using our LCSR-based method in combination with two different types of pion distribution amplitudes and found that at higher Q2 it approaches a constant.