Revisiting rescattering contributions to ${\overline{B}}_{(s)}\to D_{(s)}^{(\ast )}M$ decays

Abstract

Motivated by the reported discrepancies between experimental data and Standard Model predictions for the branching ratios of the color-allowed decays ${\overline{B}}^0\to D^{(\ast )+}{K}^{-}$ and ${\overline{B}}_s^0\to D_s^{(\ast )+}{\pi }^{-}$, we study final-state rescattering effects on ${\overline{B}}_{(s)}\to D_{(s)}^{(\ast )}P$ 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 ${\overline{B}}_{(s)}\to D_{(s)}^{(\ast )}P$ 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.

Comments: 26 pages, 10 figures, 4 tables, Published version