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

Abstract

A measurement of the CKM angle $\gamma$ using the decay channels $B^{\pm}\rightarrow DK^{\pm}$ and $B^{\pm}\rightarrow D\pi^{\pm}$, where the $D$ meson decays to $D\rightarrow K_{\rm S}^{0}\pi^{+}\pi^{-}$ or $D\rightarrow K_{\rm S}^{0}K^{+}K^{-}$, is performed with a data sample corresponding to an integrated luminosity of 5.8 fb$^{-1}$, collected during 2024 by the upgraded LHCb experiment. $C\!P$ 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.