Radiative decays of light-quark mesons to a pion revisited in the covariant oscillator quark model

TL;DR

This paper revisits the covariant oscillator quark model to analyze radiative decays of light-quark mesons, clarifying the nature of bilocal meson fields and successfully predicting decay widths consistent with experimental data.

Contribution

It introduces a refined treatment of bilocal meson fields in the covariant oscillator quark model and applies this to accurately calculate radiative decay widths of light-quark mesons.

Findings

Calculated decay widths agree with experimental data for most mesons.

Supports recent experimental results over PDG averages for certain decay widths.

Clarifies the bosonic or fermionic nature of bilocal meson fields depending on quark content.

Abstract

The present talk consists of two parts. The first one is allocated for consideration of the dimension of bilocal meson fields for quark-antiquark meson systems, which have been so far treated as the bosonic fields independent of constituent quark flavors, in the covariant oscillator quark model. Revisiting the electromagnetic currents of quark-antiquark meson systems, we show that the bilocal meson fields should be bosonic for light-quark meson systems, while fermionic for heavy-light and heavy-heavy meson systems. In the second part we apply the effective electromagnetic interactions of meson systems derived in the first part to radiative decay processes for the excited states of light-quark mesons. The calculated results for the $\pi \gamma$ decay widths of the $a_1(1260)$, $a_2(1320)$, $b_1(1235)$ and $\pi_2(1670)$ mesons are in fair agreement with experiment, except for the $b_1(1235)$ meson. As for the $\rho(770)^0 \gamma$ decay width of the $f_1(1285)$ the present model strongly supports the experimental results in 1995 and 2016, respectively, of VES and CLAS Collaborations, not the average value by the Particle Data Group.