Improved Measurement of Time-Dependent CP Asymmetries and the CP-Odd Fraction in the Decay $B^0 \to D^ *+ D^ *- $

We present an updated measurement of the CP-odd fraction and the time-dependent CP asymmetries in the decay B0->D*+D*-using (383 +/- 4) \times 10^{6} BB pairs collected with the Babar detector. We determine the CP-odd fraction to be 0.143±0.034\stat±0.008\syst0.143±0.034\stat±0.008\syst. The time-dependent CP asymmetry parameters are determined to be C+=−0.05±0.14\stat±0.02\systC+=−0.05±0.14\stat±0.02\syst and S+=−0.72±0.19\stat±0.05\systS+=−0.72±0.19\stat±0.05\syst. The non-zero value of the measured S+S+ indicates the evidence of CP violation at the 3.7σ3.7σ confidence level.