Measurement of the branching fraction of $D_s^{+}\to {\tau }^{+}{\nu }_{\tau }$ via ${\tau }^{+}\to {\mu }^{+}{\nu }_{\mu }\overline{{\nu }_{\tau }}$

Abstract

Utilizing $7.33{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ collision data taken at the center-of-mass energies of 4.128, 4.157, 4.178, 4.189, 4.199, 4.209, 4.219, and 4.226 GeV with the BESIII detector, the branching fraction of the leptonic decay $D_s^{+}\to {\tau }^{+}{\nu }_{\tau }$ via ${\tau }^{+}\to {\mu }^{+}{\nu }_{\mu }{\bar{\nu }}_{\tau }$ is measured to be ${\mathcal{B}}_{D_s^{+}\to {\tau }^{+}{\nu }_{\tau }}=(5.34\pm 0.16_{\mathrm{stat}}\pm 0.10_{\mathrm{syst}})\%$. Combining this branching fraction with the world averages of the measurements of the masses of ${\tau }^{+}$ and $D_s^{+}$ as well as the lifetime of $D_s^{+}$, we extract the product of the decay constant of $D_s^{+}$ and the $c\to s$ Cabibbo-Kobayashi-Maskawa matrix element to be $f_{D_s^{+}}|V_{cs}|=(246.2\pm 3.7_{\mathrm{stat}}\pm 2.5_{\mathrm{syst}})\mathrm{MeV}$. Taking $|V_{cs}|$ from a global fit in the standard model we obtain $f_{D_s^{+}}=(252.7\pm 3.8_{\mathrm{stat}}\pm 2.6_{\mathrm{syst}})$ MeV. Conversely, taking $f_{D_s^{+}}$ from lattice quantum chromodynamics calculations, we obtain $|V_{cs}|=0.984\pm 0.015_{\mathrm{stat}}\pm 0.010_{\mathrm{syst}}$.

arXiv comment26 pages, 8 figures

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Cited by in corpus (4)

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• Updated measurement of the branching fraction of $D_s^{+}\to {\tau }^{+}{\nu }_{\tau }$ via ${\tau }^{+}\to {\pi }^{+}{\bar{\nu }}_{\tau }$
• Charm Physics at the Super $\tau$-Charm Factory
• Measurement of the branching fraction of $D_s^{+}\to {\ell }^{+}{\nu }_{\ell }$ via $e^{+}{e}^{-}\to D_s^{\ast +}{D}_s^{\ast -}$