Heavy Quarkonium π^+π^- Transitions and a Possible b\bar{b}q\bar{q} State

F. -K. Guo, P. -N. Shen, H. -C. Chiang +1

${\pi }^{+}{\pi }^{-}$ transitions of heavy quarkonia, especially the ${\rm Y}(3S)\to {\rm Y}(1S){\pi }^{+}{\pi }^{-}$ decay process, are revisited. In the framework of the Chiral Unitary Theory (ChUT), the $S$ wave $\pi \pi$…