Search for $CP$ violation in the $D^{+}\to {\pi }^{+}{\pi }^0$ decay at Belle

We search for $CP$ violation in the charged charm meson decay $D^{+}\to {\pi }^{+}{\pi }^0$, based on a data sample corresponding to an integrated luminosity of $921\mathrm{f}{\mathrm{b}}^{-1}$ collected by the Belle experiment at the KEKB $e^{+}{e}^{-}$ asymmetric-energy collider. The measured $CP$ violating asymmetry is $[+2.31\pm 1.24(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t})\pm 0.23(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t})]\mathrm{\%}$, which is consistent with the standard model prediction and has a significantly improved precision compared to previous results.