Determination of the Anomalous Chiral Coefficients of order $p^{6}$

TL;DR

This paper determines the anomalous chiral coefficients at order p^6 in Chiral Perturbation Theory by fitting experimental data and tests the validity of VMD and CQM models in describing anomalous processes.

Contribution

It provides the first phenomenological determination of the p^6 anomalous chiral coefficients and evaluates the effectiveness of VMD and CQM models against experimental data.

Findings

Successful fit of several p^6 coefficients using experimental data

Validation of VMD and CQM models in the anomalous sector

Insights into the structure of anomalous chiral Lagrangian

Abstract

Symmetries affected by the anomaly do not survive quantization and cannot be understood classically. They are of fundamental importance and offer an opportunity of expanding the theoretical framework. We examine the theory of the anomalous sector, starting from lowest order Chiral Perturbation Theory (ChPT), leading up to the construction of the recently developed Lagrangian of $\mathcal{O}(p^{6}) $ describing anomalous processes. This Lagrangian contains a set of chiral coefficients that must be determined phenomenologically. Using currently available experimental data, we fit as many of these coefficients as possible. The results of the ChPT treatment are then used to test the validity of the two main alternative models employed in the anomalous sector - Vector Meson Dominance (VMD) and the constituent Chiral Quark Model (CQM).