BESIII Completes Collection of 20fb-1ψ(3770) Data


The Beijing Spectrometer III (BESIII) collaboration completed its ψ(3770) data collection, achieving an integrated luminosity of 20 fb-1 at the Beijing Electron Positron Collider II (BEPCII) on Feb. 24, 2024. This dataset represents the largest sample of data near the threshold of charmed-anticharmed meson pairs in the world, offering unique advantages such as quantum correlation, low background, and high detection efficiency. These data are irreplaceable for determining decay constants and transition form factors of charmed mesons, as well as for conducting amplitude analyses of multi-body charmed meson decays, measuring relative strong phases of different complex amplitudes in neutral charmed meson decays to hadronic final states, and studying rare charmed meson decays.


The BESIII experiment has achieved a series of world-leading important results using 2.93 fb-1 of ψ(3770) data collected in 2010 and 2011, including the phase difference in the D0→KS π+π - decay, the discovery of the D+→Ksa0(980)+ decay, the observation of the abnormal branching fraction of the doubly Cabibbo-suppressed decay D+→K+π+π -π0, precise studies of the dynamics of D0→K- -e+νe, studies of D0→K-μ+νμ dynamics and lepton universality tests, the discoveries of D+→f0(500)e+νe, D0(+)→a0(980)e+νe and D+→K1(1270)0e+νe, and more.


Since the 2021–2022 run period, the BESIII experiment has collected an additional 17 fb-1 of ψ(3770) data, bringing the accumulated integrated luminosity of ψ(3770) data to 20 fb-1, thus completing the data volume planned in the BESIII Physics Yellow Book published in 2008. The successful collection of this substantial amount of data will allow the BESIII experiment to precisely test the standard model and gain a deeper understanding of the nonperturbative nature of strong interactions with unprecedented precision, thereby enabling China to continue to lead in the field of experimental research in τ-charm physics.


The Beijing Electron Positron Collider II (BEPCII) has successfully completed the collision task for ψ(3770) data with high quality, maintaining long-term stability above the design value, and achieving a peak luminosity of 1.1×1033 cm-2s-1, thus setting the highest record in the history of BEPC.

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Ms. JIA Yinghua