Search for $CP$ violation in $D_{(s)}^{+}\to h^{+}{\pi }^0$ and $D_{(s)}^{+}\to h^{+}\eta$ decays

Abstract

Searches for $CP$ violation in the two-body decays $D_{(s)}^{+}\to h^{+}{\pi }^0$ and $D_{(s)}^{+}\to h^{+}\eta$ (where $h^{+}$ denotes a ${\pi }^{+}$ or $K^{+}$ meson) are performed using $pp$ collision data collected by the LHCb experiment corresponding to either 9 fb${}^{-1}$ or 6 fb${}^{-1}$ of integrated luminosity. The ${\pi }^0$ and $\eta$ mesons are reconstructed using the $e^{+}{e}^{-}\gamma$ final state, which can proceed as three-body decays ${\pi }^0\to e^{+}{e}^{-}\gamma$ and $\eta \to e^{+}{e}^{-}\gamma$, or via the two-body decays ${\pi }^0\to \gamma \gamma$ and $\eta \to \gamma \gamma$ followed by a photon conversion. The measurements are made relative to the control modes $D_{(s)}^{+}\to K_S^0{h}^{+}$ to cancel the production and detection asymmetries. The $CP$ asymmetries are measured to be \begin{align} \mathcal{A}_{CP}(D^{+}\rightarrow π^{+}π^{0}) &= (-1.3 \pm 0.9 \pm 0.6 )\%, \end{align} \begin{align} \mathcal{A}_{CP}(D^{+}\rightarrow K^{+}π^{0}) &= (-3.2 \pm 4.7 \pm 2.1 )\%, \end{align} \begin{align} \mathcal{A}_{CP}(D^{+}\rightarrow π^{+}η) &= (-0.2 \pm 0.8 \pm 0.4 )\%, \end{align} \begin{align} \mathcal{A}_{CP}(D^{+}\rightarrow K^{+}η) &= (-6 \pm 10 \pm 4 )\%, \end{align} \begin{align} \mathcal{A}_{CP}(D_{s}^{+}\rightarrow K^{+}π^{0}) &= (-0.8 \pm 3.9 \pm 1.2 )\%, \end{align} \begin{align} \mathcal{A}_{CP}(D_{s}^{+}\rightarrow π^{+}η) &= (0.8 \pm 0.7 \pm 0.5 )\%, \end{align} \begin{align} \mathcal{A}_{CP}(D_{s}^{+}\rightarrow K^{+}η) &= (0.9 \pm 3.7 \pm 1.1 )\%, \end{align} where the first uncertainties are statistical and the second systematic. These results are consistent with no $CP$ violation and mostly constitute the most precise measurements of ${\mathcal{A}}_{CP}$ in these decay modes to date.

All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2021-001.html (LHCb public pages)

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• Observation of $CP$ violation in charm decays
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Cited by in corpus (6)

• Averages of $b$-hadron, $c$-hadron, and $\tau$-lepton properties as of 2021
• Recent advances in charm mixing and $CP$ violation at LHCb
• Lepton universality violation from neutral pion decays in $R_{K^{(\ast )}}$ measurements
• Measurement of the CP asymmetry in $D^{+}\to {\pi }^{+}{\pi }^0$ decays at Belle II
• A Review of $CP$ Violation Measurements in Charm at LHCb
• Search for $D^{+}\to K^{-}{K}_s^0{\pi }^{+}{\pi }^{+}{\pi }^0$ at Belle