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Observation of CP Violation in Charm Decays

Research output: Contribution to journalArticle

Original languageEnglish
Article number211803
JournalPhysical Review Letters
Issue number21
Early online date29 May 2019
Publication statusPublished - 31 May 2019


A search for charge-parity (CP) violation in D0→K-K+ and D0→π-π+ decays is reported, using pp collision data corresponding to an integrated luminosity of 5.9  fb-1 collected at a center-of-mass energy of 13 TeV with the LHCb detector. The flavor of the charm meson is inferred from the charge of the pion in D*(2010)+→D0π+ decays or from the charge of the muon in B¯→D0μ-ν¯μX decays. The difference between the CP asymmetries in D0→K-K+ and D0→π-π+ decays is measured to be ΔACP=[-18.2±3.2(stat)±0.9(syst)]×10-4 for π-tagged and ΔACP=[-9±8(stat)±5(syst)]×10-4 for μ-tagged D0 mesons. Combining these with previous LHCb results leads to ΔACP=(-15.4±2.9)×10-4, where the uncertainty includes both statistical and systematic contributions. The measured value differs from zero by more than 5 standard deviations. This is the first observation of CP violation in the decay of charm hadrons.

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