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Evidence for the Direct Two-Photon Transition from ψ(3686) to J/ψ

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journal contribution
posted on 24.10.2012, 00:00 authored by Roy BriereRoy Briere, C. L. Liu, BESIII Collaboration

The two-photon transition ψ(3686)→γγJ/ψ is studied in a sample of 1.06×108 ψ(3686) decays collected by the BESIII detector. The branching fraction is measured to be (3.1±0.6(stat)+0.8−1.0(syst))×10−4 using J/ψ→e+e− and J/ψ→μ+μ− decays, and its upper limit is estimated to be 4.5×10−4 at the 90% confidence level. This work represents the first measurement of a two-photon transition among charmonium states. The orientation of the ψ(3686) decay plane and the J/ψ polarization in this decay are also studied. In addition, the product branching fractions of sequential E1transitions ψ(3686)→γχcJ and χcJ→γJ/ψ(J=0,1,2) are reported.

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© 2012 American Physical Society

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24/10/2012

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