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

<!--HTML-->Searches for $CP$ violation in the two-body decays $D_{(s)}^{+}\rightarrow h^{+}\pi^{0}$ and $D_{(s)}^{+} \rightarrow h^{+}\eta$ (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 $\pi^{0}\rightarrow e^{+}e^{-}\gamma$ and $\eta \rightarrow e^{+}e^{-}\gamma$, or via the two-body decays $\pi^{0}\rightarrow \gamma\gamma$ and $\eta\rightarrow\gamma\gamma$ followed by a photon conversion. The measurements are made relative to the control modes $D_{(s)}^{+}\rightarrow K_{S}^{0} h^{+}$ to cancel the production and detection asymmetries. The $CP$ asymmetries are measured to be <br> $\mathcal{A}_{CP}(D^{+}\rightarrow \pi^{+}\pi^{0}) = (-1.3 \pm 0.9 \pm 0.6 )%$, <br> $\mathcal{A}_{CP}(D^{+}\rightarrow K^{+}\pi^{0}) = (-3.2 \pm 4.7 \pm 2.1 )%$, <br> $\mathcal{A}_{CP}(D^{+}\rightarrow \pi^{+}\eta) = (-0.2 \pm 0.8 \pm 0.4 )\%$, <br> $\mathcal{A}_{CP}(D^{+}\rightarrow K^{+}\eta) = (-6 \pm 10 \pm 4 )%$, <br> $\mathcal{A}_{CP}(D_{s}^{+}\rightarrow K^{+}\pi^{0}) = (-0.8 \pm 3.9 \pm 1.2 )%$, <br> $\mathcal{A}_{CP}(D_{s}^{+}\rightarrow \pi^{+}\eta) = (0.8 \pm 0.7 \pm 0.5 )%$, <br> $\mathcal{A}_{CP}(D_{s}^{+}\rightarrow K^{+}\eta) = (0.9 \pm 3.7 \pm 1.1 )%$, <br> 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.