Observation of the electromagnetic Dalitz decay D*0 → D0e+e-

作者：Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Amoroso, A.; An, M. R.; An, Q.; Bai, X. H.; Bai, Y.; Bakina, O.; Ferroli, R. Baldini; Balossino, I; Ban, Y.; Begzsuren, K.; Berger, N.; Bertani, M.; Bettoni, D.; Bianchi, F.; Bloms, J.; Bortone, A.; Boyko, I; Briere, R. A.; Cai, H.; Cai, X.; Calcaterra, A.; Cao, G. F.; Cao, N.; Cetin, S. A.; Chang, J. F.; Chang, W. L.; Chelkov, G.; Chen, D. Y.; Chen, G.; Chen, H. S.; Chen, M. L.; Chen, S. J.; Chen, X. R.

来源：Physical Review D, 2021, 104(11): 112012.

DOI：10.1103/PhysRevD.104.112012

• PHI

Based on 3.19 fb(-1) of e(+) e(-) collision data accumulated at the center-of-mass energy 4.178 GeV with the BESIII detector operating at the BEPCII collider, the electromagnetic Dalitz decay D*(0) -> D(0)e(+)e(-) is observed for the first time with a statistical significance of 13.2 sigma. The ratio of the branching fraction of D*(0) -> D(0)e(+)e(-) to that of D*(0) -> D-0 gamma is measured to be (11.08 +/- 0.76 +/- 0.49) x 10(-3). By using the world average value of the branching fraction of D*(0) -> D-0 gamma, the branching fraction of D*(0) -> D(0)e(+)e(-) is determined to be (3.91 +/- 0.27 +/- 0.17 +/- 0.10) x 10(-3), where the first uncertainty is statistical, the second is systematic and the third is from external input of the branching fraction for D*(0) -> D-0 gamma.