Observation of e+e−→π+π−π0χb1,2(1P) and search for e+e−→ϕχb1,2(1P) at s=10.96—11.05 GeV
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Abstract
We report searches for the processes ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{\ensuremath{\chi}}_{bJ}$ and ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\ensuremath{\phi}{\ensuremath{\chi}}_{bJ}$ ($\mathrm{J}=1$, 2) based on data samples collected by the Belle experiment at the KEKB collider. We report the first observation of the process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}({\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{)}_{\mathrm{non}\ensuremath{-}\ensuremath{\omega}}{\ensuremath{\chi}}_{b1}$ and first evidence for ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\ensuremath{\omega}{\ensuremath{\chi}}_{bJ}$ in the vicinity of the $\mathrm{\ensuremath{\Upsilon}}(11020)$ resonance, with center-of-mass energies from 10.96 to 11.05 GeV. The significances for $({\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{)}_{\mathrm{non}\ensuremath{-}\ensuremath{\omega}}{\ensuremath{\chi}}_{b1}$ and $\ensuremath{\omega}{\ensuremath{\chi}}_{bJ}$ are greater than $5.3\ensuremath{\sigma}$ and $4.0\ensuremath{\sigma}$, respectively. We also investigate the energy dependence of the ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{\ensuremath{\chi}}_{bJ}$ cross section, but we cannot determine whether the contributions are from the $\mathrm{\ensuremath{\Upsilon}}(10860)$ and $\mathrm{\ensuremath{\Upsilon}}(11020)$ resonances or nonresonant continuum processes. The signals for ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\ensuremath{\phi}{\ensuremath{\chi}}_{bJ}$ are not significant, and the upper limits of the Born cross sections at the 90% confidence level are 0.7 and 1.0 pb for ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\ensuremath{\phi}{\ensuremath{\chi}}_{b1}$ and $\ensuremath{\phi}{\ensuremath{\chi}}_{b2}$, respectively, for center-of-mass energies from 10.96 to 11.05 GeV.