Color suppressed contributions to the decay modes $B_{d,s} \to D_{s,d} D_{s,d} $ , $B_{d,s} \to D_{s,d} D^*_{s,d}$ , and $B_{d,s} \to D^*_{s,d} D^*_{s,d} $

Abstract

The amplitudes for decays of the type $B_{d,s} \to D_{s,d} D_{s,d} $ , have no factorizable contributions, while $B_{d,s} \to D_{s,d} D^*_{s,d}$ , and $B_{d,s} \to D^*_{s,d} D^*_{s,d} $ have relatively small factorizable contributions through the annihilation mechanism. The dominant contributions to the decay amplitudes arise from chiral loop contributions and tree level amplitudes which can be obtained in terms of soft gluon emissions forming a gluon condensate. We predict that the branching ratios for the processes $\bar B^0_d \to D_s^ + D_s^-$ , $\bar B^0_d \to D_s^{ + *} D_s^- $ and $\bar B^0_d \to D_s^ + D_s^{-*}$ are all of order (2- 3) x 10-4, while $\bar B^0_s \to D_d^ + D_d^-$ , $\bar B^0_s \to D_d^{ + *} D_d^- $ and $\bar B^0_s \to D_d^ + D_d^{-*}$ are of order (4- 7) x 10-3. We obtain branching ratios for two D*’s in the final state of order two times bigger.