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

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 ${\kern 0.18em \overline{\kern -0.18em B}\to{D^{*}(2010)^{+}} \mu^{-} X}$ 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 ${A_{D}=(2.3\pm1.7)\,{\%}}$.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 $\overline{B}\to {D}^{\ast }{(2010)}^{+}{\mu}^{-}X$ 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) %.[graphic not available: see fulltext]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 ${A_{D}=(2.3\pm1.7)\,{\%}}$