Radiative Decays, Nonet Symmetry and SU(3) Breaking

TL;DR

This paper uses the Hidden Local Symmetry model to analyze light meson radiative and leptonic decays, achieving good data agreement and insights into pseudoscalar mixing angles and symmetry breaking effects.

Contribution

It demonstrates that a specific SU(3) symmetry breaking scheme combined with nonet symmetry breaking effectively describes light meson decays within the HLS model.

Findings

Achieves good agreement with most decay data

Determines pseudoscalar mixing angle ~ -11°

Identifies difficulty in disentangling nonet symmetry breaking and glue effects

Abstract

We re-examine the problem of simultaneously describing in a consistent way all radiative and leptonic decays of light mesons (V -> P gamma, P -> V gamma, P -> gamma gamma, V -> e^+ e^-). For this purpose, we rely on the Hidden Local Symmetry model in both its anomalous and non--anomalous sectors. We show that the SU(3) symmetry breaking scheme proposed by Bando, Kugo and Yamawaki, supplemented with nonet symmetry breaking in the pseudoscalar sector, allows one to reach a nice agreement with all data, except for the K^{*+/-} radiative decay. An extension of this breaking pattern allows one to account for this particular decay mode too. Considered together, the whole set of radiative decays provides a pseudoscalar mixing angle theta_P ~ -11^o and a value for theta_V which is ~ 3^o from that of ideal mixing. We also show that it is impossible, in a practical sense, to disentangle the effects of nonet symmetry breaking and those of glue inside the eta', using only light meson decays.