We measure the lifetime of the $D_s^{+}$ meson using a data sample of $207{\mathrm{fb}}^{-1}$ collected by the Belle II experiment running at the SuperKEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The lifetime is determined by fitting the decay-time distribution of a sample of $116\times {10}^3$ $D_s^{+}\to \varphi {\pi }^{+}$ decays. Our result is ${\tau }_{D_s^{+}}=(499.5\pm 1.7\pm 0.9)\mathrm{fs}$, where the first uncertainty is statistical and the second is systematic. This result is significantly more precise than previous measurements.

• Received 1 June 2023
• Accepted 14 September 2023

DOI:https://doi.org/10.1103/PhysRevLett.131.171803

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Published by the American Physical Society