Measurement of the Absolute Branching Fraction of $D_s^{+}\to {\tau }^{+}{\nu }_{\tau }$ via ${\tau }^{+}\to e^{+}{\nu }_e{\bar{\nu }}_{\tau }$

Abstract

Using a dataset of 6.32 fb${}^{-1}$ of $e^{+}{e}^{-}$ annihilation data collected with the BESIII detector at center-of-mass energies between 4178 and 4226 MeV, we have measured the absolute branching fraction of the leptonic decay $D_s^{+}\to {\tau }^{+}{\nu }_{\tau }$ via ${\tau }^{+}\to e^{+}{\nu }_e{\bar{\nu }}_{\tau }$, and find ${\mathcal{B}}_{D_s^{+}\to {\tau }^{+}{\nu }_{\tau }}=(5.27\pm 0.10\pm 0.12)\times 10^{-2}$, where the first uncertainty is statistical and the second is systematic. The precision is improved by a factor of 2 compared to the previous best measurement. Combining with $f_{D_s^{+}}$ from Lattice quantum chromodynamics calculations or the $|V_{cs}|$ from the CKMfitter group, we extract $|V_{cs}|=0.978\pm 0.009\pm 0.012$ and $f_{D_s^{+}}=(251.1\pm 2.4\pm 3.0)$ MeV, respectively. Combining our result with the world averages of ${\mathcal{B}}_{D_s^{+}\to {\tau }^{+}{\nu }_{\tau }}$ and ${\mathcal{B}}_{D_s^{+}\to {\mu }^{+}{\nu }_{\mu }}$, we obtain the ratio of the branching fractions ${\mathcal{B}}_{D_s^{+}\to {\tau }^{+}{\nu }_{\tau }}/{\mathcal{B}}_{D_s^{+}\to {\mu }^{+}{\nu }_{\mu }}=9.72\pm 0.37$, which is consistent with the standard model prediction of lepton flavor universality.

8 pages, 2 figures

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Cited by in corpus (9)

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• Recent Progress in Leptonic and Semileptonic Decays of Charmed Hadrons
• Updated measurement of the branching fraction of $D_s^{+}\to {\tau }^{+}{\nu }_{\tau }$ via ${\tau }^{+}\to {\pi }^{+}{\bar{\nu }}_{\tau }$
• Improved measurement of the branching fraction of $D_s^{+}\to {\mu }^{+}{\nu }_{\mu }$
• Measurement of the branching fraction of $D_s^{+}\to {\ell }^{+}{\nu }_{\ell }$ via $e^{+}{e}^{-}\to D_s^{\ast +}{D}_s^{\ast -}$
• Measurement of the absolute branching fraction of the inclusive decay $D_s^{+}\to {\pi }^{+}{\pi }^{+}{\pi }^{-}X$
• Precision Measurement of the Branching Fraction of $D^{+}\to {\mu }^{+}{\nu }_{\mu }$
• Feasibility Study of $D_s^{+}\to {\tau }^{+}{\nu }_{\tau }$ Decay and Test of Lepton Flavor Universality with Leptonic $D_s^{+}$ Decays at STCF