• Open Access

Measurement of the branching fraction of leptonic decay Ds+τ+ντ via τ+π+π0ν¯τ

M. Ablikim et al. (BESIII Collaboration)
Phys. Rev. D 104, 032001 – Published 13 August 2021

Abstract

By analyzing 6.32fb1 of e+e annihilation data collected at the center-of-mass energies between 4.178 and 4.226 GeV with the BESIII detector, we determine the branching fraction of the leptonic decay Ds+τ+ντ, with τ+π+π0ν¯τ, to be BDs+τ+ντ=(5.29±0.25stat±0.20syst)%. We estimate the product of the Cabibbo-Kobayashi-Maskawa matrix element |Vcs| and the Ds+ decay constant fDs+ to be fDs+|Vcs|=(244.8±5.8stat±4.8syst)MeV, using the known values of the τ+ and Ds+ masses as well as the Ds+ lifetime, together with our branching fraction measurement. Combining the value of |Vcs| obtained from a global fit in the standard model and fDs+ from lattice quantum chromodynamics, we obtain fDs+=(251.6±5.9stat±4.9syst)MeV and |Vcs|=0.980±0.023stat±0.019syst. Using the branching fraction of BDs+μ+νμ=(5.35±0.21)×103, we obtain the ratio of the branching fractions BDs+τ+ντ/BDs+μ+νμ=9.89±0.71, which is consistent with the standard model prediction of lepton flavor universality.

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  • Received 17 May 2021
  • Accepted 7 July 2021

DOI:https://doi.org/10.1103/PhysRevD.104.032001

Published 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 Society

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Vol. 104, Iss. 3 — 1 August 2021

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