Hadroproduction of ${\rm Y}(nS)$ above $B\bar{B}$ Thresholds and Implications for $Y_b(10890)$

Abstract

Based on the non-relativistic QCD factorization scheme, we study the hadroproduction of the bottomonium states ${\rm Y}(5S)$ and ${\rm Y}(6S)$. We argue to search for them in the final states ${\rm Y}(1S,2S,3S){\pi }^{+}{\pi }^{-}$, which are found to have anomalously large production rates at ${\rm Y}(5S)$. The enhanced rates for the dipionic transitions in the ${\rm Y}(5S)$-energy region could, besides ${\rm Y}(5S)$, be ascribed to $Y_b(10890)$, a state reported by the Belle collaboration, which may be interpreted as a tetraquark. The LHC/Tevatron measurements are capable of making a case in favor of or against the existence of $Y_b(10890)$, as demonstrated here. Dalitz analysis of the ${\rm Y}(1S,2S,3S){\pi }^{+}{\pi }^{-}$ states from the ${\rm Y}(5S)/Y_b(10890)$ decays also impacts directly on the interpretation of the charged bottomonium-like states, $Z_b(10600)$ and $Z_b(10650)$, discovered by Belle in these puzzling decays.

Comments: 6 pages, 2 figures; v2: new estimates of color-octet contributions, and comparison with the recent CMS data