Study of Υ(3S,2S)→ηΥ(1S) and Υ(3S,2S)→π+π-Υ(1S) hadronic transitions
Abstract
We study the Υ(3S,2S)→ηΥ(1S) and Υ(3S,2S) →π +π -Υ(1S) transitions with 122×106Υ(3S) and 100×106Υ(2S) mesons collected by the BABAR detector at the PEP-II asymmetric-energy e +e - collider. We measure B[Υ(2S)→ηΥ(1S)]=(2.39±0.31(stat.) ±0.14(syst.))×10 -4 and Γ[Υ(2S) →ηΥ(1S)]/Γ[Υ(2S)→π +π -Υ(1S)]=(1.35±0.17(stat.)±0.08(syst.)) ×10 -3. We find no evidence for Υ(3S)→ηΥ(1S) and obtain B[Υ(3S)→ηΥ(1S)]<1.0×10 -4 and Γ[Υ(3S)→ηΥ(1S)]/Γ[Υ(3S)→π +π -Υ(1S)]<2.3×10 -3 as upper limits at the 90% confidence level. We also provide improved measurements of the Υ(2S)-Υ(1S) and Υ(3S)-Υ(1S) mass differences, 562.170±0.007(stat.)±0.088(syst.)MeV/c2 and 893.813±0. 015(stat.)±0.107(syst.)MeV/c2, respectively. © 2011 American Physical Society.
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