Updated measurement of decay-time-dependent CP asymmetries in $D^0\to K^{+}{K}^{-}$ and $D^0\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}$ decays

Abstract

A search for decay-time-dependent charge-parity ($CP$) asymmetry in $D^0\to K^{+}{K}^{-}$ and $D^0\to \ddot{I}{€}^{+}\ddot{I}{€}^{-}$ decays is performed at the LHCb experiment using proton-proton collision data recorded at a center-of-mass energy of 13TeV, and corresponding to an integrated luminosity of 5.4fb${}^{-1}$. 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 $A_{\hat{I}}“(K^{+}{K}^{-})=(-4.3\pm 3.6\pm 0.5)\times 10^{-4}$ and $A_{\hat{I}}“(\ddot{I}{€}^{+}\ddot{I}{€}^{-})=(2.2\pm 7.0\pm 0.8)\times 10^{-4}$, where the uncertainties are statistical and systematic, respectively. The results are consistent with $CP$ symmetry and, when combined with previous LHCb results, yield $A_{\hat{I}}“(K^{+}{K}^{-})=(-4.4\pm 2.3\pm 0.6)\times 10^{-4}$ and $A_{\hat{I}}“(\ddot{I}{€}^{+}\ddot{I}{€}^{-})=(2.5\pm 4.3\pm 0.7)\times 10^{-4}$.

All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2019-032.html (LHCb public pages)