Observation of CP violation in B^0 -> eta' K^0 Decays

TL;DR

This paper reports the observation of CP violation in B^0 -> eta' K^0 decays, measuring time-dependent parameters with high statistical significance, confirming CP violation in this decay mode.

Contribution

First measurement of CP-violation parameters S and C in B^0 -> eta' K^0 decays using a large data sample, establishing mixing-induced CP violation with high significance.

Findings

Measured S = 0.58 ± 0.10 ± 0.03

Measured C = -0.16 ± 0.07 ± 0.03

Observed CP violation with 5.5 sigma significance

Abstract

We present measurements of the time-dependent CP-violation parameters S and C in B^0 --> eta' K^0 decays. The data sample corresponds to 384 million B Bar pairs produced by e^+ e^- annihilation at the Y(4S). The results are S = 0.58 +- 0.10 +- 0.03 and C = -0.16 +- 0.07 +- 0.03. We observe mixing-induced CP violation with a significance of 5.5 standard deviations in this b -> s penguin dominated mode.