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)-1.0+0.8(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 E1 transitions ψ(3686)→γχcJ and χcJ→γJ/ψ(J=0,1,2) are reported.
Evidence for the Direct Two-Photon Transition from ψ(3686) to J/ψ
DESTEFANIS, MARCO GIOVANNI;GRECO, Michela;MAGGIORA, MARCO;SPATARO, STEFANO GIOVANNI;
2012-01-01
Abstract
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)-1.0+0.8(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 E1 transitions ψ(3686)→γχcJ and χcJ→γJ/ψ(J=0,1,2) are reported.File | Dimensione | Formato | |
---|---|---|---|
PhysRevLett.109.172002.pdf
Accesso aperto
Tipo di file:
PDF EDITORIALE
Dimensione
319.16 kB
Formato
Adobe PDF
|
319.16 kB | Adobe PDF | Visualizza/Apri |
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.