A search for decay-time-dependent charge-parity ($CP$) asymmetry in ${D}^{0}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}$ and ${D}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ decays is performed at the LHCb experiment using proton-proton collision data recorded at a center-of-mass energy of 13 TeV, and corresponding to an integrated luminosity of $5.4\text{ }\text{ }{\text{fb}}^{\ensuremath{-}1}$. The ${D}^{0}$ mesons are required to originate from semileptonic decays of $b$ hadrons, such that the charge of the muon identifies the flavor of the neutral $D$ meson at production. The asymmetries in the effective decay widths of ${D}^{0}$ and ${\overline{D}}^{0}$ mesons are determined to be ${A}_{\mathrm{\ensuremath{\Gamma}}}({K}^{+}{K}^{\ensuremath{-}})=(\ensuremath{-}4.3\ifmmode\pm\else\textpm\fi{}3.6\ifmmode\pm\else\textpm\fi{}0.5)\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}4}$ and ${A}_{\mathrm{\ensuremath{\Gamma}}}({\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})=(2.2\ifmmode\pm\else\textpm\fi{}7.0\ifmmode\pm\else\textpm\fi{}0.8)\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}4}$, where the uncertainties are statistical and systematic, respectively. The results are consistent with $CP$ symmetry and, when combined with previous LHCb results, yield ${A}_{\mathrm{\ensuremath{\Gamma}}}({K}^{+}{K}^{\ensuremath{-}})=(\ensuremath{-}4.4\ifmmode\pm\else\textpm\fi{}2.3\ifmmode\pm\else\textpm\fi{}0.6)\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}4}$ and ${A}_{\mathrm{\ensuremath{\Gamma}}}({\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})=(2.5\ifmmode\pm\else\textpm\fi{}4.3\ifmmode\pm\else\textpm\fi{}0.7)\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}4}$.
Tópico:
Particle physics theoretical and experimental studies