Towards the establishment of the lightJ^P(C)=1^–(+)hybrid nonet

Abstract：

The observation of the light hybrid candidate $ \eta_1(1855) $ by the BESIII Collaboration offers great opportunities for advancing our knowledge on exotic hadrons in terms of flavor sector. We demonstrate 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 deduce that the SU(3) flavor octet and singlet mixing is non-negligible and apparently deviates from the flavor ideal mixing. Because 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 either be 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 $ denote the light vector mesons and $ 1^{-(+)} $ hybrid states, respectively, may provide further evidence for this nonet structure and ultimately establish these mysterious exotic species in the experiment.