Updated measurement of the branching fraction of D⁺_s → τ⁺ν_τ via τ⁺ → π⁺¯ν_τ

This paper reports the study of Dþ s → τþν via τþ → πþν¯ τ using a boosted decision tree method, with 7.33 fb−1 of eþe− collision data collected by the BESIII detector at center-of-mass energies between 4.128 and 4.226 GeV. The branching fraction of Dþ s → τþντ is determined to be ð5.44 0.17stat 0.13systÞ%. The product of the Dþ s decay constant fDþ s and the Cabibbo-Kobayashi-Maskawa matrix element jVcsj is fDþ s jVcsj¼ð248.3 3.9stat 3.1syst 1.0inputÞ MeV. Combining with the jVcsj value obtained from the Standard Model global fit or the fDþ s from the lattice quantum chromodynamics, we determine jVcsj ¼ 0.993 0.015stat 0.012syst 0.004input and fDþ
s ¼ ð255.0 4.0stat 3.2syst 1.0inputÞ MeV. The first uncertainty is statistical, the second one is systematic and the third one is due to the input parameters,
mainly the lifetime of Dþ s . All results obtained in this work supersede the BESIII previous results based on 6.32 fb−1 of eþe− collision data taken at center-of-mass energies between 4.178 and 4.226 GeV.