Publication: Observation of the Dalitz decay eta ' -> gamma e(+)e(-)
Date
Authors
TAPAN, İLHAN
Authors
Ablikim, M.
Achasov, M. N.
Ai, X. C.
Albayrak, O.
Albrecht, M.
Ambrose, D. J.
Amoroso, A.
An, F. F.
An, Q.
Bai, J. Z.
Advisor
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Amer Physical
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Abstract
We report the first observation of the Dalitz decay eta' -> gamma e(+)e(-), based on a data sample of 1.31 billion J/psi events collected with the BESIII detector. The eta' mesons are produced via the J/psi -> gamma eta' decay process. The ratio (eta' -> gamma e(+)e(-))/Gamma (eta' -> gamma gamma) is measured to be (2.13 +/- 0.09(stat) +/- 0.07(sys)) x 10(-2). This corresponds to a branching fraction B(eta' -> gamma e(+)e(-)) = (4.69 +/- 0.20(stat) +/- 0.23(sys)) x 10(-4). The transition form factor is extracted and different expressions are compared to the measured dependence on the e(+)e(-) invariant mass. The results are consistent with the prediction of the vector meson dominance model.
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Keywords
Form-factors, Dominance, Pi-0, Astronomy & astrophysics, Physics