Decays of Zb -> Upsilon + pi via triangle diagrams in heavy meson molecules

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Bottomonium-like resonances Zb(10610) and Zb'(10650) are good candidates of hadronic molecules composed of BBbar* (or B*Bbar) and B*Bbar*, respectively. Considering Zb (Zb') as heavy meson molecules, we investigate the decays of Zb(')+ -> Upsilon (nS) pi+ in terms of the heavy meson effective theory. We find that the intermediate B (B*) and Bbar (Bbar*) meson loops and the form factors play a significant role to reproduce the experimental values of the decay widths. We also predict the decay widths of Zc+ -> J/ψpi+ and psi(2S) pi+ for a charmonium-like resonance Zc which has been reported recently in experiments.