Soft Matrix Elements in Non-local Chiral Quark Model

TL;DR

This paper employs a non-local chiral quark model to analyze photon and pion-to-photon distribution amplitudes and transition distribution amplitudes, revealing their structure, polynomiality, and form factors consistent with experimental data.

Contribution

It introduces a detailed analysis of DA and TDA within a non-local chiral quark model, including analytical calculations up to twist-4 and validation against experimental data.

Findings

Photon DAs calculated up to twist-4 reveal structural features.

TDA's satisfy polynomiality condition.

Axial form factor is significantly lower than the vector form factor, matching experimental observations.

Abstract

Using non-local chiral quark model and currents satisfying Ward-Takahashi identities we analyze Distribution Amplitudes (DA) of photon and pion-to-photon Transition Distribution Amplitudes (TDA) in the low energy regime. Photon DA's are calculated analytically up to twist-4 and reveal several interesting features of photon structure. TDA's calculated in the present model satisfy polynomiality condition. Normalization of vector TDA is fixed by the axial anomaly. We also compute relevant form factors and compare them with existing data. Axial form factor turns out to be much lower then the vector one, what indeed is seen in the experimental data.