Towards the establishment of the light $J^{P(C)}=1^{-(+)}$ hybrid nonet

TL;DR

This paper explores the potential existence of a light hybrid nonet with specific quantum numbers, using the flux tube model to analyze production and decay mechanisms, and suggests experimental channels for its detection.

Contribution

It proposes the establishment of a $J^{P(C)}=1^{-(+)}$ hybrid nonet based on recent observations and flux tube model analysis, including mixing effects and detection strategies.

Findings

SU(3) flavor mixing deviates from ideal mixing

Only one isoscalar $ ext{η}_1(1855)$ observed in $ ext{η} ext{η'}$ channel

Suggested experimental channels for hybrid detection

Abstract

The observation of the light hybrid candidate $\eta_1(1855)$ by the BESIII Collaboration brings great opportunities for advancing our knowledges about exotic hadrons in the light flavor sector. We show that this observation provides a crucial clue for establishing the $J^{P(C)}=1^{-(+)}$ hybrid nonet. Based on the flux tube model picture, the production and decay mechanisms for the $J^{P(C)}=1^{-(+)}$ hybrid nonet in the $J/\psi$ radiative decays into two pseudoscalar mesons are investigated. In the $I=0$ sector, we find that the SU(3) flavor octet and singlet mixing is non-negligible and apparently deviates from the flavor ideal mixing. Since only signals for one isoscalar $\eta_1(1855)$ are observed in the $\eta\eta'$ channel, we investigate two schemes of the nonet structure in which $\eta_1(1855)$ can be either the higher or lower mass state that strongly couples to $\eta\eta'$. Possible channels for detecting the multiplets are suggested. In particular, a combined analysis of the hybrid production in $J/\psi\to VH$, where $V$ and $H$ stand for the light vector mesons and $1^{-(+)}$ hybrid states, may provide further evidence for this nonet structure and finally establish these mysterious exotic species in experiment.