Study of $\eta$ and dipion transitions in ${\rm Y}(4S)$ decays to lower bottomonia

Abstract

We study hadronic transitions between bottomonium states using 496 fb${}^{-1}$ data collected at the ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB asymmetric energy $e^{+}{e}^{-}$ collider. We measure: $\mathcal{B}({\rm Y}(4S)\to {\pi }^{+}{\pi }^{-}{\rm Y}(1S))=(8.2\pm 0.5(stat.)\pm 0.4(syst.))\times 10^{-5}$, $\mathcal{B}({\rm Y}(4S)\to {\pi }^{+}{\pi }^{-}{\rm Y}(2S))=(7.9\pm 1.0(stat.)\pm 0.4(syst.))\times 10^{-5}$, and $\mathcal{B}({\rm Y}(4S)\to \eta {\rm Y}(1S))=(1.70\pm 0.23(stat.)\pm 0.08(syst.))\times 10^{-4}$. We measure the ratio of branching fractions $\mathcal{R}=\mathcal{B}({\rm Y}(4S)\to \eta {\rm Y}(1S))/\mathcal{B}({\rm Y}(4S)\to {\pi }^{+}{\pi }^{-}{\rm Y}(1S))=2.07\pm 0.30(stat.)\pm 0.11(syst.)$. We search for the decay ${\rm Y}(1^3{D}_{1,2})\to \eta {\rm Y}(1S)$, but do not find significant evidence for such a transition. We also measure the initial state radiation production cross sections of the ${\rm Y}(2S,3S)$ resonances and we find values compatible with the expected ones. Finally, the analysis of the ${\rm Y}(4S)\to {\pi }^{+}{\pi }^{-}{\rm Y}(1S)$ events shows indications for a resonant contribution due to the $f_0(980)$ meson.

arXiv comment11 pages, 7 figures, 6 tables. Submitted to PRD

References in corpus (20)

• A Unified Approach to the Classical Statistical Analysis of Small Signals
• sPlot: a statistical tool to unfold data distributions
• Observation of two charged bottomonium-like resonances in Y(5S) decays
• Charmonium
• Observation of anomalous Upsilon(1S)pi+pi- and Upsilon(2S)pi+pi- production near the Upsilon(5S) resonance
• Electron Identification in Belle
• Spectroscopy at B-factories Using Hard Photon Emission
• Evidence for Large Direct CP Violation in B+-=>rho(770)0K+- from Analysis of the Three-Body Charmless B+-=>K+-pi+-pi-+ Decay
• QCD Multipole Expansion and Hadronic Transitions in Heavy Quarkonium Systems
• Amplitude analysis of e+e- => Y(nS)pi+pi- at sqrt(s)=10.865 GeV
• Observation of ${\rm Y}(4S)decaysto$π^+pi^-Υ(1S)$and$π^+pi^-Υ(2S)
• Effects of $Z_b$ states and bottom meson loops on ${\rm Y}(4S)\to {\rm Y}(1S,2S){\pi }^{+}{\pi }^{-}$ transitions
• Study of Di-Pion Transitions Among Upsilon(3S), Upsilon(2S), and Upsilon(1S) States
• Study of hadronic transitions between Y states and observation of Y(4S)-> eta Y(1S) decay
• First observation of the hadronic transition ${\rm Y}(4S)\to \eta h_b(1P)$ and new measurement of the $h_b(1P)$ and ${\eta }_b(1S)$ parameters
• Two-pion transitions in quarkonium revisited
• Study of Upsilon(3S,2S) -> eta Upsilon(1S) and Upsilon(3S,2S) -> pi+pi- Upsilon(1S) hadronic trasitions
• The enhancement of the decay Upsilon(1D) -> eta Upsilon(1S) by the axial anomaly in QCD
• Measurement of the branching fraction for the decay Upsilon(4S) -> Upsilon(1S)pi+pi-
• Single eta production in heavy quarkonia: breakdown of multipole expansion

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• Chromopolarizabilities of bottomonia from the ${\rm Y}(2S,3S,4S)\to {\rm Y}(1S,2S)\pi \pi$ transitions
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