Measurement of Time-Dependent CP-Violating Asymmetries in B0 --> phi Ks0, K+ K- Ks0, and eta' Ks0 Decays

TL;DR

This paper reports an improved measurement of CP-violation parameters in specific B0 meson decays, revealing a significant deviation from the Standard Model in the B0 --> phi Ks0 decay, using data from the Belle detector.

Contribution

The study provides the most precise CP-violation measurements in these decay modes to date, highlighting a potential discrepancy with the Standard Model in B0 --> phi Ks0 decay.

Findings

CP asymmetry in B0 --> phi Ks0 differs from SM by 3.5 sigma

Other decay modes are consistent with SM expectations

Enhanced measurement precision with 140 fb-1 data sample

Abstract

We present an improved measurement of CP-violation parameters in B0 --> phi Ks0, K+ K- Ks0, and eta' Ks0 decays based on a 140 fb-1 data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB energy-asymmetric e+e- collider. One neutral B meson is fully reconstructed in one of the specified decay channels, and the flavor of the accompanying B meson is identified from its decay products. CP-violation parameters for each of the three modes are obtained from the asymmetries in the distributions of the proper-time intervals between the two B decays. We find that the observed CP asymmetry in the B0 --> phi Ks0 decay differs from the standard model (SM) expectation by 3.5 standard deviations, while the other cases are consistent with the SM.