Model-independent approach to eta -> pi+ pi- gamma and eta' -> pi+ pi- gamma

TL;DR

This paper introduces a novel, model-independent analytical method combining chiral perturbation and dispersion theories to study meson radiative decays into pion pairs, avoiding explicit vector meson dominance assumptions.

Contribution

The paper develops a new analytical approach for meson decay analysis that integrates chiral and dispersion theories without relying on vector meson dominance.

Findings

Successfully applied to eta and eta' decays

Provides controlled inclusion of resonance physics

Avoids explicit vector meson dominance

Abstract

We present a new, model-independent method to analyze radiative decays of mesons to a vector, isovector pair of pions of invariant mass square below the first significant pion-pion threshold in the vector channel. It is based on a combination of chiral perturbation theory and dispersion theory. This allows for a controlled inclusion of resonance physics without the necessity to involve vector meson dominance explicitly. As an example, the method is applied to an analysis of the reactions eta -> pi+ pi- gamma and eta'->pi+ pi- gamma.