Abstract
A search for charge-parity (CP) violation in D^{0}→K^{-}K^{+} and D^{0}→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 13TeV with the LHCb detector. The flavor of the charm meson is inferred from the charge of the pion in D^{*}(2010)^{+}→D^{0}π^{+} decays or from the charge of the muon in B[over ¯]→D^{0}μ^{-}ν[over ¯]_{μ}X decays. The difference between the CP asymmetries in D^{0}→K^{-}K^{+} and D^{0}→π^{-}π^{+} decays is measured to be ΔA_{CP}=[-18.2±3.2(stat)±0.9(syst)]×10^{-4} for π-tagged and ΔA_{CP}=[-9±8(stat)±5(syst)]×10^{-4} for μ-tagged D^{0} mesons. Combining these with previous LHCb results leads to ΔA_{CP}=(-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.
Highlights
A search for charge-parity (CP) violation in D0 → K−Kþ and D0 → π−πþ 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 realization of CP violation in weak interactions has been established in the K- and B-meson systems by several experiments [4,5,6,7,8,9,10,11,12], and all results are well interpreted within the CKM formalism
The size of CP violation in the standard model (SM) appears to be too small to account for the observed matter-antimatter asymmetry [13,14,15], suggesting the existence of sources of CP violation beyond the SM
Summary
A search for charge-parity (CP) violation in D0 → K−Kþ and D0 → π−πþ 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. This Letter presents a measurement of the difference of the time-integrated CP asymmetries in D0 → K−Kþ and D0 → π−πþ decays, performed using pp collision data collected with the LHCb detector at a center-of-mass energy of 13 TeV, and corresponding to an integrated luminosity of 5.9 fb−1.
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