We measure the $B^0$ lifetime and flavor-oscillation frequency using $B^0\to D^{(*)-}{\pi }^{+}$ decays collected by the Belle II experiment in asymmetric-energy $e^{+}{e}^{-}$ collisions produced by the SuperKEKB collider operating at the $\mathrm{\Upsilon }(4\mathrm{S})$ resonance. We fit the decay-time distribution of signal decays, where the initial flavor is determined by identifying the flavor of the other $B$ meson in the event. The results, based on 33000 signal decays reconstructed in a data sample corresponding to $190{\mathrm{fb}}^{-1}$, are ${\tau }_{B^0}=(1.499\pm 0.013\pm 0.008)\mathrm{ps}$, $\mathrm{\Delta }{m}_d=(0.516\pm 0.008\pm 0.005){\mathrm{ps}}^{-1}$, where the first uncertainties are statistical and the second are systematic. These results are consistent with the world-average values.

• Received 27 February 2023
• Accepted 18 April 2023

DOI:https://doi.org/10.1103/PhysRevD.107.L091102

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Published by the American Physical Society