On the structure of the pi pi invariant mass spectra of the Upsilon(4S)-->Upsilon(1S,2S) pi^+ pi^- decays

Abstract

We perform a model-independent analysis for recently reported data of the ${\pi }^{+}{\pi }^{-}$ invariant mass spectra in the ${\rm Y}(4S)\to {\rm Y}(1S,2S){\pi }^{+}{\pi }^{-}$ decays and point out that there does exist a broad peak below 0.6 GeV in the data of the ${\rm Y}(4S)\to {\rm Y}(1S){\pi }^{+}{\pi }^{-}$ decay, which is analogous to that in the ${\rm Y}(3S)\to {\rm Y}(1S){\pi }^{+}{\pi }^{-}$ decay. With the data of ${\rm Y}(4S)$ decays, we further test our model developed for studying the puzzle in the ${\rm Y}(3S)\to {\rm Y}(1S){\pi }^{+}{\pi }^{-}$ decay. The result shows that with such a model, all the ${\pi }^{+}{\pi }^{-}$ invariant mass spectra of ${\rm Y}(4S)$ decays can be described. We also predict the $\cos {\theta }_{\pi }^{\ast }$ distributions of ${\rm Y}(4S)\to {\rm Y}(1S,2S){\pi }^{+}{\pi }^{-}$ decays, which can be used to justify our model prediction.

11 pages, 5 figures. Extended to include new data; title changed. Version accepted for publication in Phys. Lett. B

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• The Cosmological Parameters 2006
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• Observation of ${\rm Y}(4S)decaysto$π^+pi^-Υ(1S)$and$π^+pi^-Υ(2S)
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Cited by in corpus (9)

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• Scalar Resonance Contributions to the Dipion Transition Rates of ${\rm Y}(4S,5S)$ in the re-scattering model
• Charged bottomonium-like states $Z_b(10610)$ and $Z_b(10650)$ and the ${\rm Y}(5S)\to {\rm Y}(2S){\pi }^{+}{\pi }^{-}$ decay
• Effects of $Z_b$ states and bottom meson loops on ${\rm Y}(4S)\to {\rm Y}(1S,2S){\pi }^{+}{\pi }^{-}$ transitions
• Bottomonium dipion transitions
• Hadron physics potential of future high-luminosity B-factories at the Upsilon(5S) and above
• Anomalous dipion invariant mass distribution of the ${\rm Y}(4S)$ decays into ${\rm Y}(1S){\pi }^{+}{\pi }^{-}$ and ${\rm Y}(2S){\pi }^{+}{\pi }^{-}$
• Search for $B_c(ns)$ via the $B_c(ns)\to B_c(ms){\pi }^{+}{\pi }^{-}$ transition at LHCb and $Z_0$ factory
• Exotic hadrons associated with $b$-quark