Improved Measurement of the Cabibbo-Kobayashi-Maskawa Angle α Using B0(B¯)→ρ+ρ− Decays
B. Aubert, R. Barate, D. Boutigny, F. Couderc et autres
We present results from an analysis of ${B}^{0}({\overline{B}}^{0})\ensuremath{\rightarrow}{\ensuremath{\rho}}^{+}{\ensuremath{\rho}}^{\ensuremath{-}}$ using $232\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $\ensuremath{\Upsilon}(4S)\ensuremath{\rightarrow}B\overline{B}$ decays collected with the BABAR detector at the PEP-II asymmetric-energy $B$ factory at SLAC. We measure the longitudinal polarization fraction ${f}_{L}=0.978\ifmmode\pm\else\textpm\fi{}0.014(\mathrm{stat})\genfrac{}{}{0}{}{+0.021}{\ensuremath{-}0.029}(\mathrm{syst})$ and the $CP$-violating parameters ${S}_{L}=\ensuremath{-}0.33\ifmmode\pm\else\textpm\fi{}0.24(\mathrm{stat})\genfrac{}{}{0}{}{+0.08}{\ensuremath{-}0.14}(\mathrm{syst})$ and ${C}_{L}=\ensuremath{-}0.03\ifmmode\pm\else\textpm\fi{}0.18(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.09(\mathrm{syst})$. Using an isospin …
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