Observation of CP violation in charm decays at LHCb

Abstract

A search for charge-parity (CP) violation in $D^0\to K^{-}{K}^{+}$ and $D^0\to {\pi }^{-}{\pi }^{+}$ decays is reported, using $pp$ collision data corresponding to an integrated luminosity of 5.9 ${\mathrm{fb}}^{-1}$ collected at a center-of-mass energy of 13 TeV with the LHCb detector. The flavor of the $D^0$ meson is determined from the charge of the pion in $D^{\ast }(2010{)}^{+}\to D^0{\pi }^{+}$ decays or from the charge of the muon in $\overline{B}\to D^0{\mu }^{-}{\bar{\nu }}_{\mu }X$ decays. The difference between the CP asymmetries in $D^0\to K^{-}{K}^{+}$ and $D^0\to {\pi }^{-}{\pi }^{+}$ decays is measured to be $\Delta A_{\mathrm{CP}}=[-18.2\pm 3.2(stat.)\pm 0.9(syst.)]\times 10^{-4}$ for $\pi$-tagged and $\Delta A_{\mathrm{CP}}=[-9\pm 8(stat.)\pm 5(syst.)]\times 10^{-4}$ for $\mu$-tagged $D^0$ mesons. The combination with previous LHCb results leads to $$\Delta A_{\mathrm{CP}}=(-15.4\pm 2.9)\times 10^{-4},$$ where the uncertainty includes both statistical and systematic contributions. The measured value differs from zero by more than five standard deviations. This is the first observation of CP violation in the decay of charm hadrons.

Contribution to the 2019 EW session of the 54th Rencontres de Moriond

References in corpus (8)

• Observation of $CP$ violation in charm decays
• New Physics and CP Violation in Singly Cabibbo Suppressed D Decays
• Measurement of the D+/- production asymmetry in 7 TeV pp collisions
• Direct CP asymmetry in $D\to {\pi }^{-}{\pi }^{+}$ and $D\to K^{-}{K}^{+}$ in QCD-based approach
• On Indirect CP Violation and Implications for D0-\overline{D0} and Bs -\overline{Bs} mixing
• Source of CP Violation for the Baryon Asymmetry of the Universe
• On $SU(3{)}_F$ Breaking through Final State Interactions and CP Asymmetries in $D\to PP$ Decays
• CP violation for neutral charmed meson decays to CP eigenstates