Analysis of the $b_1$ meson decay in local tensor bilinear representation

TL;DR

This paper investigates the decay of the $b_1(1235)$ meson, revealing a violation of vector meson dominance due to tensor bilinear interactions and the role of an $ ext{omega}$-like hybrid state.

Contribution

It introduces a tensor bilinear representation model for the $b_1$ meson decay, explaining the deviation from vector meson dominance and highlighting the significance of an $ ext{omega}$-like hybrid state.

Findings

The $b_1$ decay process does not follow the usual vector meson dominance.

An $ ext{omega}$-like hybrid state influences the decay mechanism.

Spectral analysis suggests a $ ext{pi}$-$ ho$ hybrid structure for the intermediate state.

Abstract

We explore the validity of vector meson dominance in the radiative decay of the $b_1(1235)$ meson. In order to explain the violation of the vector meson dominance hypothesis in this decay process, we investigate a model where the $b_1$ meson strongly couples with the local current in tensor bilinear representation. The tensor representation is investigated in the framework of the operator product expansion and we found a low energy decay process that does not follow the usual vector meson dominance hypothesis. The $\omega$-like intermediate meson state of quantum numbers $I^G(J^{PC}) = 0^{-}(1^{--})$ is found to have a nontrivial role in the decay process of the $b_1$ meson. The spectral structure of the $\omega$-like state is found to be close to a $\pi$-$\rho$ hybrid state, which provides a mechanism that evades the usual vector meson dominance hypothesis. Precise measurements of various decay channels of the $b_1$ meson are, therefore, required to unravel the internal structure of axial vector mesons.