Feasibility study of Ds+→τ+ντ decay and test of lepton flavor universality with leptonic Ds+ decays at STCF

• Main Authors: Li, H. (Author), Luo, T. (Author), Shi, X. (Author), Zhou, X. (Author)
• Format: Article
• Language: English
• Published: Springer Science and Business Media Deutschland GmbH 2022
• Online Access: View Fulltext in Publisher

 We report a sensitive study of Ds+→τ+ντ decay via τ+→ e+νeν¯ τ with an integrated luminosity of 1 ab- 1 at the center-of-mass energy of 4.009 GeV at a future Super Tau Charm Facility (STCF). Under the help of the fast simulation software package, the statistical sensitivity for the absolute branching fraction of Ds+→τ+ντ is determined to be 2 × 10 - 4. Combining with our previous prospect of Ds+→μ+νμ, the ratio of the branching fractions for Ds+→τ+ντ over Ds+→μ+νμ can achieve a relative statistical precision of 0.5%, which will provide the most stringent test of the τ-μ lepton flavor universality in heavy quark decays. Taking the decay constant fDs+ from lattice QCD calculations or the CKM matrix element | Vcs| from the CKMfitter group as an input, the relative statistical uncertainties for | Vcs| and fDs+ are estimated to be 0.3% and 0.2%, respectively. © 2022, The Author(s).