Measurements of branching fractions and time-dependent CP violating asymmetries in B0→D( ^*) ^±D ^∓ decays

We report measurements of branching fractions and time-dependent CP asymmetries in B0→D ⁺D ^- and B0→D ^*±D ^∓ decays using a data sample that contains (772±11)×106BB̄ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e ⁺e ^- collider. We determine the branching fractions to be B(B0→D ⁺D ^-)=(2.12±0.16±0.18) ×10 ^-4 and B(B0→D ^{* ±}D ^∓)=(6.14±0.29±0.50) ×10 ^-4. We measure CP asymmetry parameters SD ⁺D ^-=-1.06-0.14+0.21±0.08 and CD ⁺D ^-=-0. 43±0.16±0.05 in B0→D ⁺D ^- and AD ^*D=+0.06±0.05±0.02, SD ^*D=-0. 78±0.15±0.05, CD ^*D=-0.01±0.11±0.04, ΔSD ^*D=-0.13±0.15±0.04 and ΔCD ^*D=+0.12±0.11±0.03 in B0→D ^*±D ^∓, where the first uncertainty is statistical and the second is systematic. We exclude the conservation of CP symmetry in both decays at equal to or greater than 4σ significance.