Precise measurement of the $D_s^{+}$ lifetime at Belle II

Abstract

We measure the lifetime of the $D_s^{+}$ meson using a data sample of 207 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 $116\times 10^3$ $D_s^{+}\to \ddot{I}•\ddot{I}{€}^{+}$ decays. Our result is $\ddot{I}{„}_{D_s^{+}}^{}=(499.5\pm 1.7\pm 0.9)$ fs, where the first uncertainty is statistical and the second is systematic. This result is significantly more precise than previous measurements.

7 pages, 4 figures, as published in Physical Review Letters