Radiative decay into $\gamma P$ of the low lying axial-vector mesons

TL;DR

This paper calculates the radiative decay widths of axial-vector mesons into a pseudoscalar meson and a photon, considering both tree level and loop diagrams, revealing a wide range of decay widths and analyzing the two $K_1(1270)$ states.

Contribution

It provides a comprehensive evaluation of radiative decay widths of axial-vector mesons generated from vector-pseudoscalar interactions, including the two $K_1(1270)$ states, with detailed theoretical predictions.

Findings

Large variation in radiative decay widths among axial-vector mesons.

Identification of two $K_1(1270)$ states with distinct decay properties.

Discussion of experimental data in light of the two-state scenario.

Abstract

We evaluate the radiative decay into a pseudoscalar meson and a photon of the whole set of the axial-vector mesons dynamically generated from the vector-pseudoscalar meson ($VP$) interaction. We take into account tree level and loop diagrams coming from the axial-vector decay into a vector and a pseudoscalar meson. We find a large span for the values of the radiative widths of the different axial-vector mesons. In particular, we evaluate the radiative decay into $K \gamma$ of the two $K_1(1270)$ states, recently claimed theoretically, and discuss the experimental values quoted so far on the assumption of only one state.