2022/08/25 by BESIII Collaboration, М. Н. Ачасов, M. Ablikim +577 · 1 voice
Physics and Astronomy · #Algorithm #Black Holes and Theoretical Physics #Computer science #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #hep-ex
paper · pdf · doi:10.1103/physrevd.106.112002
arxiv published 2022/08/25 · openalex publication_date 2022/12/07 · openalex created_date 2022/12/21 · arxiv updated 2023/10/26 · openalex updated_date 2026/08/04
Using a data sample of (448.1\ifmmode±\else\textpm\fi2.9)\ifmmode×\else\texttimes\fi106 \ensuremathψ(3686) decays collected at an e+e^\ensuremath- center-of-mass energy of 3.686 GeV by the BESIII detector at Beijing Electron Positron Collider II, we report an observation of the hindered electromagnetic Dalitz decay \ensuremathψ(3686)\ensuremath→e+e^\ensuremath-\ensuremathηc with a significance of 7.9\ensuremathσ. The branching fraction is determined to be B(\ensuremathψ(3686)\ensuremath→e+e^\ensuremath-\ensuremathηc)=(3.77\ifmmode±\else\textpm\fi0.40stat\ifmmode±\else\textpm\fi0.18syst)\ifmmode×\else\texttimes\fi10^\ensuremath-5, agreeing well with the prediction of the vector meson dominance model. This is the first measurement of the electromagnetic Dalitz transition between the \ensuremathψ(3686) and the \ensuremathηc, which provides new insight into the electromagnetic properties of this decay, and offers new opportunities to measure the absolute branching fractions of \ensuremathηc decays.