Observation of Time-Dependent CP Violation in B0 -> eta' K0 Decays and Improved Measurements of CP Asymmetries in B0 -> phiK0, KsKsKs and B0 -> J/psi K0 Decays

TL;DR

This paper reports precise measurements of CP violation in various B0 meson decays, confirming CP violation in B0->eta'K0 with high significance and improving the accuracy of other decay measurements using a large data sample.

Contribution

It provides the first observation of CP violation in B0->eta'K0 and offers improved measurements of CP asymmetries in multiple B0 decay channels with a large data set.

Findings

CP violation observed in B0->eta'K0 with 5.6 sigma significance

Improved measurements of sin2phi_1 in B0->J/psiK0 decays

Precise CP asymmetry parameters for B0->phiK0 and KsKsKs decays

Abstract

We present improved measurements of CP-violation parameters in B0->phiK0, eta'K0, KsKsKs decays based on a sample of 535x10^6 BBbar pairs collected at the Y(4S) resonance with the Belle detector at the KEKB energy-asymmetric e+e- collider. We obtain sin2phi_1^eff=+0.64+-0.10(stat)+-0.04(syst) for B0->eta'K0, +0.50+-0.21(stat)+-0.06(syst) for B0->phiK0, and +0.30+-0.32(stat) +-0.08(syst) for B0->KsKsKs decays. We have observed CP violation in the B0->eta'K0 decay with a significance of 5.6 standard deviations. We also perform an improved measurement of CP asymmetries in B0->J/psiK0 decays and obtain sin2phi_1=+0.642+- 0.031(stat)+-0.017(syst).