On the ${\eta }^{\prime }$ Gluonic Admixture

Abstract

The ${\eta }^{\prime }$ which is an $SU(3{)}_F$ singlet state can contain a pure gluon component, gluonium. We examine this possibility by analysing all available experimental data. It is pointed out that the ${\eta }^{\prime }$ gluonic component may be as large as 26%. We also show that the amplitude for $J/\psi ->{\eta }^{\prime }\gamma$ decay obtains a notable contribution from gluonium.

Comments: 13 pages LaTeX, 5 eps figures