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

TL;DR

This paper suggests the existence of hidden $b\bar{b}$ tetraquarks around 10.9 GeV, based on analysis of $e^+e^- \to b\bar{b}$ cross section data from BABAR, proposing a new state distinct from known bottomonium resonances.

Contribution

It provides evidence for a new bottomonium-like tetraquark state near 10.9 GeV, analyzing existing experimental data to identify potential signals of this exotic hadron.

Findings

Identification of an additional $b\bar{b}$ state at 10.90 GeV

Possible resolution into two close mass eigenstates with 6 MeV difference

Correlation of the new state with the $Y_b(10890)$ observed by BELLE

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 $\Upsilon (5S)$ and $\Upsilon(6S)$ 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 $e^+e^- \to Y_b(10890) \to \Upsilon (1S, 2S) \pi^+ \pi^-$ due to their proximity in masses and decay widths.