Measurements of direct CP asymmetries in B→Xsγ decays using sum of exclusive decays

Le résumé fourni par la source

We measure the direct $CP$ violation asymmetry, ${A}_{CP}$, in $B\ensuremath{\rightarrow}{X}_{s}\ensuremath{\gamma}$ and the isospin difference of the asymmetry, $\mathrm{\ensuremath{\Delta}}{A}_{CP}$, using $429\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data collected at $\mathrm{\ensuremath{\Upsilon}}(4S)$ resonance with the BABAR detector at the PEP-II asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ storage rings operating at the SLAC National Accelerator Laboratory. $B$ mesons are reconstructed from ten charged $B$ final states and six neutral $B$ final states. We find ${A}_{CP}=+(1.7\ifmmode\pm\else\textpm\fi{}1.9\ifmmode\pm\else\textpm\fi{}1.0)%$, which is in agreement with the Standard Model prediction and provides an improvement on the world average. Moreover, we report the first measurement of the difference between ${A}_{CP}$ for charged and neutral decay modes, $\mathrm{\ensuremath{\Delta}}{A}_{CP}=+(5.0\ifmmode\pm\else\textpm\fi{}3.9\ifmmode\pm\else\textpm\fi{}1.5)%$. Using the value of $\mathrm{\ensuremath{\Delta}}{A}_{CP}$, we also provide 68% and 90% confidence intervals on the imaginary part of the ratio of the Wilson coefficients corresponding to the chromomagnetic dipole and the electromagnetic dipole transitions.

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