Chiral anomaly and the pion properties in the light-front quark model

TL;DR

This paper investigates how chiral symmetry and anomalies influence pion properties within a light-front quark model, highlighting the importance of anomaly effects in accurately describing experimental observables across different energy scales.

Contribution

It introduces a comprehensive analysis of chiral anomaly effects on pion properties using the light-front quark model, including axial-vector and pseudoscalar couplings, and constrains model parameters accordingly.

Findings

Chiral anomaly significantly impacts pion decay constant and form factors.

The constituent quark model effectively describes pion properties across various Q^2 ranges.

Analysis of the timelike region of $F_{ ext{pi} ext{gamma}}(Q^2)$ is crucial for understanding anomaly effects.

Abstract

We explore the link between the chiral symmetry of QCD and the numerical results of the light-front quark model, analyzing both the two-point and three-point functions of the pion. Including the axial-vector coupling as well as the pseudoscalar coupling in the light-front quark model, we discuss the implication of the chiral anomaly in describing the pion decay constant, the pion-photon transition form factor and the electromagnetic form factor of the pion. In constraining the model parameters, we find that the chiral anomaly plays a critical role and the analysis of $F_{\pi\gamma}(Q^2)$ in timelike region is important. Our results indicate that the constituent quark picture is effective for the low and high $Q^2$ ranges implementing the quark mass evolution effect as $Q^2$ grows.