Observation of direct CP violation in the measurement of the Cabibbo-Kobayashi-Maskawa angle gamma with B+- --> D(*)K(*)+- decays

TL;DR

This paper measures the CP-violating angle gamma in B meson decays, providing evidence of direct CP violation with a significance of 5.9 standard deviations, using data from the BaBar experiment.

Contribution

First measurement of gamma using multiple B decay modes with a large data set, confirming direct CP violation in B decays.

Findings

Gamma measured as (69 +17/-16) degrees

Two-standard-deviation region: 41-102 degrees

Result inconsistent with gamma=0 at 5.9 sigma

Abstract

We report the determination of the Cabibbo-Kobayashi-Maskawa CP-violating angle gamma through the combination of various measurements involving B^{+-} --> D K^{+-}, B^{+-} --> D^{*} K^{+-}, and B^{+-} --> D K^{*+-} decays performed by the BaBar experiment at the PEP-II e^{+}e^{-} collider at SLAC National Accelerator Laboratory. Using up to 474 million B\bar{B} pairs, we obtain gamma = (69 ^{+17}_{-16})^\circ (modulo 180^\circ). The total uncertainty is dominated by the statistical component, with the experimental and amplitude-model systematic uncertainties amounting to +-4^\circ. The corresponding two-standard-deviation region is 41^\circ < gamma < 102^\circ. This result is inconsistent with gamma = 0 with a significance of 5.9 standard deviations.