First evidence for the annihilation decay mode {B^{+}}\to D_s^{+}\phi

Evidence for the hadronic annihilation decay mode $ {B^{+}}\to D_s^{+}\phi $ is found with greater than 3σ significance. The branching fraction and CP asymmetry are measured to be $ \begin{array}{*{20}{c}} {\quad\;\mathcal{B}\left( {{B^{+}}\to D_s^{+}\phi } \right)=\left( {1.87_{-0.73}^{+1.25}\left( {\mathrm{stat}} \right)\pm 0.19\left( {\mathrm{syst}} \right)\pm 0.32\left( {\mathrm{norm}} \right)} \right)\times {10^{-6 }},} \hfill \\ {\,\,{{\mathcal{A}}_{CP }}\left( {{B^{+}}\to D_s^{+}\phi } \right)=-0.01\pm 0.41\left( {\mathrm{stat}} \right)\pm 0.03\left( {\mathrm{syst}} \right).} \hfill \\ \end{array} $ The last uncertainty on $ \mathcal{B}\left( {{B^{+}}\to D_s^{+}\phi } \right) $ is from the branching fractions of the $ {B^{+}}\to D_s^{+}{{\overline{D}}^0} $ normalization mode and intermediate resonance decays. Upper limits are also set for the branching fractions of the related decay modes $ B_{(c)}^{+}\to D_{(s)}^{+}{K^{*0 }},\;B_{(c)}^{+}\to D_{(s)}^{+}{{\overline{K}}^{*0 }} $ and $ B_c^{+}\to D_s^{+}\phi $ , including the result $ \mathcal{B}\left( {{B^{+}}\to {D^{+}}{K^{*0 }}} \right)<1.8\times {10^{-6 }} $ at the 90% credibility level.