Effects of $Z_b$ states and bottom meson loops on ${\rm Y}(4S)\to {\rm Y}(1S,2S){\pi }^{+}{\pi }^{-}$ transitions

Yun-Hua Chen, Martin Cleven, Johanna T. Daub +5

We study the dipion transitions ${\rm Y}(4S)\to {\rm Y}(nS){\pi }^{+}{\pi }^{-}$ $(n=1,2)$. In particular, we consider the effects of the two intermediate bottomoniumlike exotic states $Z_b(10610)…