Improved measurement of the CKM angle gamma in B^-+ -> D^(*) K^(*)-+ decays with a Dalitz plot analysis of D decays to K_S^0 pi^+ pi^- and K_S^0 K^+ K^-

TL;DR

This paper presents an improved measurement of the CP-violating phase gamma in B meson decays using Dalitz plot analysis of D meson decays, based on a large data sample from the BABAR experiment.

Contribution

It provides a more precise measurement of gamma with reduced uncertainties, including a significant evidence for direct CP violation at 3 standard deviations.

Findings

Measured gamma = (76 ± 22 ± 5 ± 5) degrees

Two standard deviation region for gamma: 29° to 122°

Evidence for direct CP violation at 3 sigma

Abstract

We report on an improved measurement of the Cabibbo-Kobayashi-Maskawa {\it CP}-violating phase $\gamma$ through a Dalitz plot analysis of neutral $D$ meson decays to $K_S^0 \pi^+ \pi^-$ and $K_S^0 K^+ K^-$ in the processes $B^\mp \to D K^\mp$, $B^\mp \to D^* K^\mp$ with $D^* \to D\pi^0,D\gamma$, and $B^\mp \to D K^{*\mp}$ with $K^{*\mp} \to K_S^0 \pi^\mp$. Using a sample of 383 million $B\bar{B}$ pairs collected by the BABAR detector, we measure $\gamma=(76 \pm 22 \pm 5 \pm 5)^\circ$ (mod $180^\circ$), where the first error is statistical, the second is the experimental systematic uncertainty and the third reflects the uncertainty on the description of the Dalitz plot distributions. The corresponding two standard deviation region is $29^\circ < \gamma < 122^\circ$. This result has a significance of direct {\it CP} violation ($\gamma \ne 0$) of 3.0 standard deviations.