Motivated by the reported discrepancies between experimental data and Standard Model predictions for the branching ratios of the color-allowed decays $\overline{ B}^0 \to D^{ (*)+}K^-$ and $\overline{ B}^0_s \to D^{ (*)+}_s \pi^-$, we study final-state rescattering effects on $\overline{ B}_{ (s)}\to D^{ (*)}_{ (s)} P$ and $\overline{ B}_{ (s)}\to D_{ (s)} V$, where $P$ ($V$) is a light pseudoscalar (vector) meson. We consider quasi-elastic rescatterings in the framework of $SU(3)$ and $U(3)$ flavor symmetries, and find that the effects cannot explain the measured branching ratios of the color-allowed and color-suppressed decays simultaneously. We also perform global fits to the $\overline{ B}_{ (s)}\to D^{ (*)}_{ (s)} P$ and $\overline{ B}_{ (s)}\to D_{ (s)} V$ data, allowing for new physics contributions to the Wilson coefficient $a_1$ associated with the color-allowed tree amplitudes. It is shown that the fits prefer a downward shift of $\mathcal{ O}(10\%)$ in $a_1$ even in the presence of the quasi-elastic rescattering contributions.
Categories: hep-ph