Radiative production and decays of the exotic <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"><mml:msubsup><mml:mrow><mml:mi>η</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>′</mml:mo></mml:mrow></mml:msubsup><mml:mo stretchy="false">(</mml:mo><mml:mn>1855</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:math> and its siblings

We study the production of light $J^{PC}=1^{-+}$ hybrid isoscalars $\eta_1^\prime(1855)$ and yet undiscovered $\eta_1(1660)$ as intermediate states in radiative decays charmonium ($J/\psi$) to two conventional mesons using a flavor symmetric Lagrangian. For this purpose, we use $J/\psi\to\gamma\eta_1^\prime(1855)\to\gamma\eta\eta^\prime$ process reference. find that some decay channels have branching ratios similar or larger than $\gamma\eta\eta^\prime$ channel are sensitive mixing between isoscalars. propose relatively stable $\gamma\eta f_1(1285)$ be explored for presence isoscalar $\eta_1(1660)$. also exploit strong containing at least one vector meson whole nonet $\{\pi_1(1600),K_1^{hyb}(1750),\eta_1(1660),\eta_1'(1855)\}$. hybrids cannot radiatively into $I=0$ pseudoscalars. Furthermore, ($(\rho/\omega/\phi)\gamma$) strangeness content hybrids. provide estimates fractions partial widths