Measurement of Time-Dependent $CP$-Violating Asymmetries in ${B}^{0}\ensuremath{\rightarrow}\ensuremath{\phi}{K}_{S}^{0}$, ${K}^{+}{K}^{\ensuremath{-}}{K}_{S}^{0}$, and ${\ensuremath{\eta}}^{\ensuremath{'}}{K}_{S}^{0}$ Decays

Measurement of Time-Dependent $C P$ -Violating Asymmetries in $B^{0} \to ϕ K_{S}^{0}$ , $K^{+} K^{-} K_{S}^{0}$ , and $η^{'} K_{S}^{0}$ Decays

K. Abe et al. (Belle Collaboration)

Phys. Rev. Lett. 91, 261602 – Published 31 December 2003

Abstract

We present an improved measurement of $C P$ -violation parameters in $B^{0} \to ϕ K_{S}^{0}$ , $K^{+} K^{-} K_{S}^{0}$ , and $η^{'} K_{S}^{0}$ decays based on a $140 {f b}^{- 1}$ data sample collected at the $Υ (4 S)$ 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. $C P$ -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 $C P$ asymmetry in the $B \to ϕ K_{S}^{0}$ decay differs from the standard model (SM) expectation by 3.5 standard deviations, while the other cases are consistent with the SM.