A case for hidden $b\bar{b}$ tetraquarks based on $e^{+}{e}^{-}\to b\bar{b}$ cross section between $\sqrt{s}=10.54$ and 11.20 GeV

Abstract

We study the spectroscopy and dominant decays of the bottomonium-like tetraquarks (bound diquarks-antidiquarks), focusing on the lowest lying P-wave $[bq][\bar{b}\bar{q}]$ states $Y_{[bq]}$ (with $q=u,d$), having $J^{PC}=1^{--}$. To search for them, we analyse the BABAR data \cite{:2008hx} obtained during an energy scan of the $e^{+}{e}^{-}\to b\bar{b}$ cross section in the range of $\sqrt{s}=10.54$ to 11.20 GeV. We find that these data are consistent with the presence of an additional $b\bar{b}$ state $Y_{[bq]}$ with a mass of 10.90 GeV and a width of about 30 MeV apart from the ${\rm Y}(5S)$ and ${\rm Y}(6S)$ resonances. A closeup of the energy region around the $Y_{[bq]}$-mass may resolve this state in terms of the two mass eigenstates, $Y_{[b,l]}$ and $Y_{[b,h]}$, with a mass difference, estimated as about 6 MeV. We tentatively identify the state $Y_{[bq]}(10900)$ from the $R_b$-scan with the state $Y_b(10890)$ observed by BELLE \cite{Abe:2007tk} in the process $e^{+}{e}^{-}\to Y_b(10890)\to {\rm Y}(1S,2S){\pi }^{+}{\pi }^{-}$ due to their proximity in masses and decay widths.

Comments: 17 pages, 2 figures; typos removed and text slightly modified; version identical to the one published in Physics Letters B