Updated measurement of decay-time-dependent CP asymmetries in D0 →k+K- A nd D0 →π+π-decays

A search for decay-time-dependent charge-parity (CP) asymmetry in D0→K+K- A nd D0→π+π-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 fb-1. The D0 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 D0 and D0 mesons are determined to be AΓ(K+K-)=(-4.3±3.6±0.5)×10-4 and AΓ(π+π-)=(2.2±7.0±0.8)×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 AΓ(K+K-)=(-4.4±2.3±0.6)×10-4 and AΓ(π+π-)=(2.5±4.3±0.7)×10-4.