A search for time-dependent violation of the charge-parity symmetry in $D^0\to K^{+}{K}^{-}$ and $D^0\to {\pi }^{+}{\pi }^{-}$ decays is performed at the LHCb experiment using proton-proton collision data recorded from 2015 to 2018 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of $6{\mathrm{fb}}^{-1}$. The $D^0$ meson is required to originate from a $D^{*}(2010{)}^{+}\to D^0{\pi }^{+}$ decay, such that its flavor at production is identified by the charge of the accompanying pion. The slope of the time-dependent asymmetry of the decay rates of $D^0$ and ${\overline{D}}^0$ mesons into the final states under consideration is measured to be $\mathrm{\Delta }{Y}_{K^{+}{K}^{-}}=(-2.3\pm 1.5\pm 0.3)\times {10}^{-4}$, $\mathrm{\Delta }{Y}_{{\pi }^{+}{\pi }^{-}}=(-4.0\pm 2.8\pm 0.4)\times {10}^{-4}$, where the first uncertainties are statistical and the second are systematic. These results are compatible with the conservation of the charge-parity symmetry at the level of 2 standard deviations and improve the precision by nearly a factor of 2.

• Received 21 May 2021
• Accepted 9 September 2021

DOI:https://doi.org/10.1103/PhysRevD.104.072010

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