Measurement ofCPviolating asymmetries inB0→K+K−KS0decays with a time-dependent Dalitz approach

Abstract

We report a measurement of CP violating asymmetries in B0(B¯0)→K+K−KS0 decays with a time-dependent Dalitz approach. This analysis is based on a data sample of 657×106 BB¯ pairs accumulated at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. As the result of an unbinned maximum likelihood fit to the selected candidates, the mixing-induced and direct CP violation parameters ϕ1eff and ACP are obtained for B0→ϕ(1020)KS0, B0→f0(980)KS0, and other B0→K+K−KS0 decays. We find four solutions that describe the data. There are ϕ1eff(B0→ϕ(1020)KS0)=(32.2±9.0±2.6±1.4)°;ϕ1eff(B0→ϕ(1020)KS0)=(26.2±8.8±2.7±1.2)°;ϕ1eff(B0→ϕ(1020)KS0)=(27.3±8.6±2.8±1.3)°;andϕ1eff(B0→ϕ(1020)KS0)=(24.3±8.0±2.9±5.2)°. The values for the CP violating phase in B0→ϕ(1020)KS0 are similar, but other properties of the Dalitz plot are quite different for the four solutions. These four solutions have consistent ϕ1eff values for all three B-meson decay channels and none of them deviates significantly from the values measured in B→(cc¯)K0 decays with the currently available statistics. In addition, we find no significant direct CP violation.Received 22 July 2010DOI:https://doi.org/10.1103/PhysRevD.82.073011© 2010 The American Physical Society