Effect of the KK‾K\overline{K} and ηη\eta\eta channels and interference phenomena in the two-pion and KK‾K\overline{K} transitions of charmonia and bottomonia

It is shown that the basic shape of dipion and $K\overline{K}$ mass spectra in decays $J/\psi\to\phi(\pi\pi,K\overline{K})$, $\psi(2S)\to J/\psi\,\pi\pi$, $Y(4260)\to J/\phi~\pi\pi$ and in the two-pion transitions of bottomonia states are explained by an unified mechanism based on the contribution of the $\pi\pi$, $K\overline{K}$ and $\eta\eta$ coupled channels including their interference. The role of the individual $f_0$ resonances in making up the shape of the dipion mass distributions in the charmonia and bottomonia decays is considered.Comment: 13 pages, 9 figure

Coupled-Channel Analysis of the Process γγ→π0π0

We study the process γγ→π0π0 involving the principal mechanisms, the structure of its cross section and the role of individual isoscalar-tensor resonances in the saturation of its energy spectrum

Coupled-Channel Analysis of the Process <i>γγ</i>→<i>π</i>⁰<i>π</i>⁰

We study the process γγ→π0π0 involving the principal mechanisms, the structure of its cross section and the role of individual isoscalar-tensor resonances in the saturation of its energy spectrum