Non-factorizable contributions to $\overline{B_d^0}\to D_s^{(\ast )}\overline{D_s^{(\ast )}}$

Abstract

It is pointed out that decays of the type $B\to D\bar{D}$ have no factorizable contributions, unless at least one of the charmed mesons in the final state is a vector meson. The dominant contributions to the decay amplitudes arise from chiral loop contributions and tree level amplitudes generated by soft gluon emissions forming a gluon condensate. We predict that the branching ratios for the processes ${\bar{B}}^0\to D_s^{+}{D}_s^{-}$, ${\bar{B}}^0\to D_s^{+\ast }{D}_s^{-}$ and ${\bar{B}}^0\to D_s^{+}{D}_s^{-\ast }$ are all of order $(3-4)\times 10^{-4}$, while ${\bar{B}}^0\to D_s^{+\ast }{D}_s^{-\ast }$ has a branching ratio 5 to 10 times bigger. We emphasize that the branching ratios are sensitive to $1/m_c$ corrections.

Comments: 4 pages, 4 figures. Based on talk by J.O. Eeg at BEACH 2004, 6th international conference on Hyperons, Charm and Beauty Hadrons, Illionois Institute of Technology, Chicago, june. 27 - july 3, 2004