ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2007, vol. 76, p. -
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 414fb-1 data sample that contains 449×106 BB̄ 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)] ×10-3, 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. 1×10-4 (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), Dsin 2 1=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 cos 2 1 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/J0sin 2 1=-0.17-0.42+0.42(stat)±0.09(syst), 2Js2/J0cos 2 1=-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 cos 2 1 given the errors. © 2007 The American Physical Society.