Search for charge-parity violation in semileptonically tagged $D^{0} \to K^{+} \pi^{-}$ decays

TL;DR

This study searches for charge-parity violation in neutral D meson decays using LHCb data, finding no significant evidence but providing precise measurements of oscillation parameters and asymmetry.

Contribution

The paper presents the first detailed search for CP violation in semileptonic D0 decays at 13 TeV with flavor tagging, improving measurement precision.

Findings

Oscillation parameters y' and x'^2 measured with uncertainties.

No evidence of CP violation detected in oscillations or decay asymmetry.

Direct CP asymmetry measured as 2.3% with uncertainty.

Abstract

An analysis of the flavour oscillations of the charmed neutral meson is presented. The ratio of $D^{0} \to K^{+} \pi^{-}$ and $D^{0} \to K^{-} \pi^{+}$ 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 $\overline{B} \to D^{*}(2010)^{+} \mu^{-} X$ and ${{D^{*}(2010)^{+}} \to D^{0}\pi^{+}}$ decays, respectively. These decays are selected from proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of ${13\,\text{TeV}}$ and corresponding to an integrated luminosity of ${5.4\,\text{fb}^{-1}}$. The flavour oscillation parameters, relating to the differences in mass and width of the mass eigenstates, are found to be ${y^\prime=(5.8\pm1.6)\times10^{-3}}$ and ${(x^\prime)^2=(0.0\pm1.2)\times10^{-4}}$. 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 ${A_{D}=(2.3\pm1.7)\,{\%}}$.