Volume 485 - The European Physical Society Conference on High Energy Physics (EPS-HEP2025) - T05 QCD and Hadronic Physics
Precision measurement of the branching fraction for the decay $\psi(2S)\rightarrow\tau^{+}\tau^{-}$ at BESIII
J.Β Zhang*, B.Β Zhang, X.Β Mo, P.Β Wang and I.Β Garzia
*: corresponding author
Full text: pdf
Pre-published on: January 26, 2026
Published on: March 11, 2026
Abstract
Using (2259.3 Β± 11.1) Γ— 106πœ“(2𝑆) events acquired with the BESIII detector, the branching
fraction of πœ“(2𝑆) β†’ 𝜏+πœβˆ’ is measured with improved precision to be π΅π‘Ÿ(πœ“(2𝑆) β†’ 𝜏+πœβˆ’) =
(3.240Β±0.023Β±0.081)Γ—10βˆ’3,wherethefirstandseconduncertaintiesarestatisticalandsystematic,
respectively, which is consistent with the world average value within one standard deviation. This
value, along with those for the branching fractions of the πœ“(2𝑆) decaying into 𝑒+π‘’βˆ’ and πœ‡+πœ‡βˆ’, is
in good agreement with the relation predicted by the sequential lepton hypothesis.
DOI: https://doi.org/10.22323/1.485.0236
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