Abstract
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→D0e+e− is observed for the first time with a statistical significance of 13.2σ. The ratio of the branching fraction of D*0→D0e+e− to that of D*0→D0γ is measured to be (11.08±0.76±0.49)×10−3. By using the world average value of the branching fraction of D*0→D0γ, the branching fraction of D*0→D0e+e− is determined to be (3.91±0.27±0.17±0.10)×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→D0γ.Received 14 November 2021Accepted 14 December 2021DOI:https://doi.org/10.1103/PhysRevD.104.112012Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasParticle decaysParticles & Fields
Highlights
third is from external input of the branching fraction
The q2 distribution depends on the underlying dynamical electromagnetic structure of the transition V
pffiBffi ased on 3.19 fb−1 of eþe− collision data collected at
Summary
The conversion decays of a vector resonance (V) into a pseudoscalar meson (P) and a lepton pair, V → Pγà → Pll , provide a stringent test for theoretical models of the structure of hadrons and the interaction mechanism between photons and hadrons [1]. In these processes, the squared dilepton invariant mass corresponds to the virtual photon four-momentum transfer squared, q2. The EM Dalitz decay DÃ0 → D0eþe− is studied and Ree is measured using 3.19 fb−1 of eþe−. The inclusion of chargeconjugate states is implied throughout this paper
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