Search for charge-parity violation in semileptonically tagged D⁰→ K⁺π⁻ decays

Abstract

Abstract An analysis of the flavour oscillations of the charmed neutral meson is presented. The ratio of D 0 → K + π

− and D 0 → K

−

π + decay rates is measured as a function of the decay time of the D 0 meson and compared with the charge-conjugated system to search for charge-parity violation. The meson flavour at production is double-tagged by the charges of the muon and pion in the preceding

$$ \overline{B}\to {D}^{\ast }{(2010)}^{+}{\mu}^{-}X $$

B ¯

→

D ∗

2010

+

μ −

X

and D ∗(2010)+ → D 0 π + decays, respectively. These decays are selected from proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 5.4 fb −1. The flavour oscillation parameters, relating to the differences in mass and width of the mass eigenstates, are found to be y′ = (5.8 ± 1.6) × 10 −3 and (x′)2 = (0.0 ± 1.2) × 10 −4. No evidence for charge-parity violation is seen either in the flavour oscillations or in the decay, where the direct charge-parity asymmetry is measured to be A

D = (2.3 ± 1.7) %.