Single eta production in heavy quarkonia transitions

Yu. A. Simonov, A. I. Veselov

The $\eta$ production in the $(n,n^{\prime })$ bottomonium transitions ${\rm Y}(n)\to {\rm Y}(n^{\prime })\eta ,$ is studied in the method used before for dipion heavy quarkonia transitions. The widths ${\Gamma }_{\eta }(n,n^{\prime })$…