Constraints on the unitarity triangle angle $\gamma$ from Dalitz plot analysis of $B^0 \to D K^+ \pi^-$ decays

The first study is presented of CP violationwith an amplitude analysis of the Dalitz plotof $B^0 \to D K^+ \pi^-$ decays, with $D \to K^+ \pi^-$, $K^+K^-$ and $\pi^+ \pi^-$. The analysis is based on a data sample corresponding to $3.0\,{\rm fb}^{-1}$ of $pp$ collisions collected with the LHCb detector. No significant CP violationeffect is seen, and constraints are placed on the angle $\gamma$ of the unitaritytriangle formed from elements of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. Hadronic parameters associated with the $B^0 \to D K^*(892)^0$ decay are determined for the first time. These measurements can be used to improve the sensitivity to $\gamma$ of existing and future studies of the $B^0 \to D K^*(892)^0$ decay.