Measurement of $\gamma$ using $B^{\pm }\to D{K}^{\pm }$ and $B^{\pm }\to D{\pi }^{\pm }$ decays with $D\to K_{\mathrm{S}}^0{\pi }^{+}{\pi }^{-}$ and $D\to K_{\mathrm{S}}^0{K}^{+}{K}^{-}$

A measurement of the CKM angle $\gamma$ using the decay channels $B^{\pm }\to D{K}^{\pm }$ and $B^{\pm }\to D{\pi }^{\pm }$, where the $D$ meson decays to $D\to K_{\mathrm{S}}^0{\pi }^{+}{\pi }^{-}$ or $D\to K_{\mathrm{S}}^0{K}^{+}{K}^{-}$, is performed with a data sample corresponding to an integrated luminosity of 5.8 fb${}^{-1}$, collected during 2024 by the upgraded LHCb experiment. $C\text{\hspace{0.17em}⁣}P$ violation is observed through a difference in the distributions of the Dalitz plot of the $D$ decay between the $B^{+}$ and $B^{-}$ mesons. The CKM angle $\gamma$ is determined to be $\gamma =(68.1\pm 6.7{)}^{\circ }$. Other parameters related to the examined $B$ meson decay modes are also measured. This is the first measurement of the CKM angle $\gamma$ using the upgraded LHCb detector.