Measurement of branching fraction and time-dependent CP asymmetry parameters in B0→D*+D*-KS0 decays

We present a measurement of the branching fraction and time-dependent CP violation parameters for B0→D*+D*-KS0 decays. These results are obtained from a 414 fb-1 data sample that contains 449x106 BB pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We obtain the branching fraction, B(B0→D*+D*-KS0)=[3.4±0.4(stat)±0.7(syst)]x10-3, which is in agreement with the current world average. We also obtain an upper limit on the product branching fraction for a possible two-body decay, B(B0→Ds1+(2536)D*-)B(Ds1+(2536)→D*+KS0)<7.1x10-4 (90% CL). In the traditional 2-parameter time-dependent CP analysis, we measure the CP violation parameters, ACP=-0.01-0.28+0.28(stat)±0.09(syst), Dsin2φ1=0.06-0.44+0.45(stat)±0.06(syst). No evidence for either mixing-induced or direct CP violation is found. In a 3-parameter fit sensitive to cos2φ1 performed in the half-Dalitz spaces, s-≤s+ and s->s+, where s±≡m2(D*±KS0), we extract the CP violation parameters, Jc/J0=0.60-0.28+0.25(stat)±0.08(syst), 2Js1/J0sin2φ1=-0.17-0.42+0.42(stat)±0.09(syst), 2Js2/J0cos2φ1=-0.23-0.41+0.43(stat)±0.13(syst). A large value of Jc/J0 would indicate a significant resonant contribution from a broad unknown Ds**+ state. Although the sign of the factor, 2Js2/J0, can be deduced from theory, no conclusion can be drawn regarding the sign of cos2φ1 given the errors