Abstract

The effect of isoscalar S-wave multichannel pi pi -> pi pi, K (K) over bar, eta eta scattering is considered in the analysis of decay data of the Y-mesons. We show that when allowing for the final state interaction contribution to the decays Y(mS) -> Y(nS)pi pi (m > n, m = 2; 3, n = 1, 2) in our model-independent approach, we can explain the two-pion energetic spectra of these Y transitions including the two-humped shape of the di-pion mass distribution in Y(3S) -> Y(1S)pi pi as the coupled-channel effect. It is shown also that the considered bottomia decay data do not offer new insights into the nature of the f(0) mesons, which were not already deduced in our previous analyses of pseudoscalar meson scattering data.