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Article

Updated measurement of decay-time-dependent CP asymmetries in D0→K+K− and D0→π+π− decays

Borisyak M., Derkach D., Guschin M., Ustyuzhanin A., Chekalina V., Boldyrev A., Arzymatov K., Belavin V., Kazeev N., Maevskiy A., Ratnikov F., Ryzhikov A., Baranov A., LHCb c.

A search for decay-time-dependent charge-parity (CP) asymmetry in D0→K+K− and D0→π+π− 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 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 D¯¯¯¯0 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.