Paper detail

Effect of coupled channels of the multi-channel pion-pion scattering in two-pion transitions of the $Υ$ mesons

The effect of isoscalar S-wave processes $ππ\toππ,K\overline{K},ηη$ is considered in the analysis of data (from the ARGUS, CLEO, CUSB, Crystal Ball, Belle, BABAR collaborations) on the bottomonia decays --- $Υ(mS)\toΥ(nS)ππ$ ($m>n, m=2,3,4,5, n=1,2,3$). It is shown that the dipion mass spectra of these decays are explained by the unified mechanism related to the contribution of the multichannel $ππ$ scattering in the final states of these reactions. Since in the analysis the multichannel $ππ$-scattering amplitudes did not change in comparison with the ones in our combined analysis of data on the multichannel $ππ$ scattering and on the charmonia decays --- $J/ψ\toϕ(ππ, K\overline{K})$ and $ψ(2S)\to J/ψ(ππ)$ (from the Crystal Ball, DM2, Mark II, Mark III, and BES II) --- the results confirm all our earlier conclusions on the scalar mesons.