Study of the suppressed B meson decay B−→DK− , D→K+π−

Le résumé fourni par la source

We report a study of the suppressed $B$ meson decay ${B}^{\ensuremath{-}}\ensuremath{\rightarrow}D{K}^{\ensuremath{-}}$ followed by $D\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, where $D$ indicates a ${D}^{0}$ or ${\overline{D}}^{0}$ state. The two decay paths interfere and provide information on the $CP$-violating angle ${\ensuremath{\phi}}_{3}$. We use a data sample containing $657\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs recorded at the $\ensuremath{\Upsilon}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ storage ring. We do not find significant evidence for the mode ${B}^{\ensuremath{-}}\ensuremath{\rightarrow}D{K}^{\ensuremath{-}}$, $D\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, and set an upper limit of ${r}_{B}<0.19$, where ${r}_{B}$ is the magnitude of the ratio of amplitudes $|A({B}^{\ensuremath{-}}\ensuremath{\rightarrow}{\overline{D}}^{0}{K}^{\ensuremath{-}})/A({B}^{\ensuremath{-}}\ensuremath{\rightarrow}{D}^{0}{K}^{\ensuremath{-}})|$. The decay ${B}^{\ensuremath{-}}\ensuremath{\rightarrow}D{\ensuremath{\pi}}^{\ensuremath{-}}$, $D\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ is also analyzed as a reference, for which we observe a signal with $6.6\ensuremath{\sigma}$ significance, and measure the charge asymmetry ${\mathcal{A}}_{D\ensuremath{\pi}}$ to be $\ensuremath{-}{0.02}_{\ensuremath{-}0.16}^{+0.15}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.04(\mathrm{syst})$. In addition, the ratio $\mathcal{B}({B}^{\ensuremath{-}}\ensuremath{\rightarrow}{D}^{0}{K}^{\ensuremath{-}})/\mathcal{B}({B}^{\ensuremath{-}}\ensuremath{\rightarrow}{D}^{0}{\ensuremath{\pi}}^{\ensuremath{-}})$ is measured to be $[6.77\ifmmode\pm\else\textpm\fi{}0.23(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.30(\mathrm{syst})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}2}$.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.