Evidence for Direct CP Violation in B0 -> K+- pi-+ Decays

TL;DR

This paper presents evidence for direct CP violation in B0 -> K+- pi-+ decays, with a significance of 3.9 sigma, based on data from the Belle detector, marking an important step in understanding matter-antimatter asymmetry.

Contribution

First observation of direct CP violation in B0 -> K+- pi-+ decays with high statistical significance using Belle data.

Findings

Measured CP asymmetry Acp(K+-pi-+) = -0.101+-0.025 (stat)+-0.005 (syst)

Evidence for CP violation with 3.9 sigma significance

No significant CP violation observed in B+- -> K+-pi0 and B+- -> pi+-pi0 decays

Abstract

We report evidence for direct CP violation in the decay B0 -> K+-pi-+ with 253/fb of data collected with the Belle detector at the KEKB e+e- collider. Using 275 million B B_bar pairs we observe a B -> K+-pi-+ signal with 2140+-53 events. The measured CP violating asymmetry is Acp(K+-pi-+) = -0.101+-0.025 (stat)+-0.005 (syst), corresponding to a significance of 3.9 sigma including systematics. We also search for CP violation in the decays B+- -> K+-pi0 and B+- -> pi+-pi0. The measured CP violating asymmetries are Acp(K+-pi0) = 0.04+-0.05(stat)+-0.02(syst) and Acp(pi+-pi0) = -0.02+-0.10(stat)+-0.01(syst), corresponding to the intervals -0.05 < Acp(K+-pi0) < 0.13 and -0.18<Acp(pi+-pi0)<0.14 at 90% confidence level.