We report the measurement of the branching fraction, the polarization, and the parameters of the time-dependent $CP$ violation in $B^0\to D^{*+}{D}^{*-}$ decays using a data sample of $772\times {10}^{6}B\overline{B}$ pairs, collected at the ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. We obtain a branching fraction of $\mathcal{B}=(7.82\pm 0.38\pm 0.63)\times {10}^{-4}$, a $CP$-odd fraction of $R_{\perp }=0.138\pm 0.024\pm 0.006$ and, additionally, a fraction of the longitudinal component in the transversity base of $R_0=0.624\pm 0.029\pm 0.011$. The measured values of the parameters of the $CP$ violation are $S_{D^{*+}{D}^{*-}}=-0.79\pm 0.13\pm 0.03$ and $A_{D^{*+}{D}^{*-}}=0.15\pm 0.08\pm 0.04$.

• Received 25 July 2012

DOI:https://doi.org/10.1103/PhysRevD.86.071103