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 13 TeV with the LHCb detector. The flavor of the charm meson is inferred from the charge of the pion in D^*(2010)^+→D^0π^+ decays or from the charge of the muon in B[over ¯]→D^0μ^-ν[over ¯]_μX 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.
Observation of CP Violation in Charm Decays
Veltri, M;
2019
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 13 TeV with the LHCb detector. The flavor of the charm meson is inferred from the charge of the pion in D^*(2010)^+→D^0π^+ decays or from the charge of the muon in B[over ¯]→D^0μ^-ν[over ¯]_μX 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.