What can we learn from $B^{+}\to D_s^{(\ast )-}{K}^{+}{\pi }^{+}$, $B_d\to D_s^{(\ast )-}{K}^0{\pi }^{+}$ and $B_d\to D_s^{(\ast )-}{K}^{\ast +}$ decays?

Abstract

We study the nonresonant three-body decays of $B^{+}\to D_s^{(\ast )-}{K}^{+}{\pi }^{+}$ and $B_d\to D_s^{(\ast )-}{K}^0{\pi }^{+}$. We find that these decays can provide the information on the time-like form factors of $D_s^{(\ast )}K$. We also explicitly investigate $B_d\to D_s^{(\ast )-}{K}^{\ast +}$ decays by discriminating the nonresonant contributions with the unknown $D_s^{(\ast )}$ wave functions being fixed by the measured mode of $B_d\to D_s^{-}{K}^{+}$.

Comments: 14 pages, 4 figures, Revtex4, version to appear in PLB