${\eta }_c$-glueball mixing and resonance X(1835)

The mixing of ${\eta }_c$ and the lowest mass pseudoscalar glueball is estimated within the framework of the instanton liquid model. It is demonstrated that the mixing is large and may explain the difference between the observed mass of the glueball candidate X(1835) and the theoretical prediction of the QCD sum rule analysis.

Figure 1

The ${\eta }_c$-pseudoscalar glueball $G_P$ mixing induced by the instanton. The symbol $I$ denotes the instanton.