Measurements of Branching Fractions for B→Kπ and B→ππ Decays

Le résumé fourni par la source

We report measurements of branching fractions for $B\ensuremath{\rightarrow}K\ensuremath{\pi}$ and $B\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi}$ decays based on a data sample of $449\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs collected at the $\ensuremath{\Upsilon}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider. We also measure the ratios of partial widths for $B\ensuremath{\rightarrow}K\ensuremath{\pi}$ decays, namely ${R}_{c}\ensuremath{\equiv}2\ensuremath{\Gamma}({B}^{+}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{0})/\ensuremath{\Gamma}({B}^{+}\ensuremath{\rightarrow}{K}^{0}{\ensuremath{\pi}}^{+})=1.08\ifmmode\pm\else\textpm\fi{}0.06\ifmmode\pm\else\textpm\fi{}0.08$ and ${R}_{n}\ensuremath{\equiv}\ensuremath{\Gamma}({B}^{0}\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})/2\ensuremath{\Gamma}({B}^{0}\ensuremath{\rightarrow}{K}^{0}{\ensuremath{\pi}}^{0})=1.08\ifmmode\pm\else\textpm\fi{}0.08\ifmmode\pm\else\textpm\fi{}0.08$, where the first and the second errors are statistical and systematic, respectively. These ratios are sensitive to enhanced electroweak penguin contributions from new physics; the new measurements are, however, consistent with standard model expectations.

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