Gluonic-bound-state model andX(2.8)

Gluonic states are discussed using a bound-state equation. We estimate masses and decay widths and point out the absence of a low-mass $0^{+}$ state. Therefore, the easiest way to observe these states is through the $\gamma \gamma$ decay mode of the $0^{-}$ particle, whose mass is about 2.8 GeV in our approximation. One candidate for the $0^{-}$ gluonic state is $X\left(2.8\right)\mathrm{}$, which was observed in a radiative decay of $\psi \mathrm{}\left(J\right)\mathrm{}$.