Mesure de l'angle gamma du triangle d'unitarité de la matrice CKM dans les désintégrations B-> D*K auprès de l'expérience BaBar

Abstract : This thesis applies the Gronau-London-Wyler (GLW) method to the $B^\pm\to D^*K^{\pm}$ decays in view of measuring the angle $\gamma$ of the unitarity triangle of the \CKM matrix at the \babar\ experiment. After a review of \CP violation, we describe the different paths used so far for measuring $\gamma$, with a special emphasis on the GLW method. Then the analysis is presented. It relies on an optimized selection for maximising signal sensitivity, and on an extended maximum likelihood fit from which we extract the four GLW observables $\mathcal A_{\CP\pm}^*$ and $\mathcal R_{\CP\pm}^*$ related to $\gamma$. Results obtained using Run 1 to 5 of \babar, corresponding to 347 fb$^{-1}$, i.e. $381\times 10^6$ $B\bar B$ pairs, give $\mathcal A_{\CP+}^*=-0,114\pm0,089\pm0,007$, $\mathcal A_{\CP-}^*=0,060\pm0,099\pm0,016$, $\mathcal R_{\CP+}^*=1,313\pm0,132\pm0,029$, $\mathcal R_{\CP-}^*=1,081\pm0,119\pm0,034$. Translated into cartesian coordinates $x_\pm^*$ for comparing with Dalitz analysis, we get $x_+^*=0,112\pm0,061\pm0,012$, $x_-^*=0,004\pm0,059\pm0,012$. All these results are in agreement with previous measurements from \babar\ an Belle when available. Precision is improved by a factor two on \CP even observables and a factor three for \CP odd observables, in particular due to the use of $D^*\to D^0\gamma$ decays, and is better on $x_\pm^*$ than the world average of \babar\ and Belle Dalitz measurements. The statistics used is too small for providing a precise enough $r_B^*$ with $\mathcal R_{\CP\pm}^*$ that could constrain $\gamma$. However the combination of our results with Dalitz measurements will improve this constraint.
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Submitted on : Sunday, December 30, 2007 - 8:42:19 PM
Last modification on : Wednesday, March 27, 2019 - 4:40:03 PM
Long-term archiving on: : Tuesday, April 13, 2010 - 3:52:52 PM

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• HAL Id : tel-00201496, version 1

Citation

E. Latour. Mesure de l'angle gamma du triangle d'unitarité de la matrice CKM dans les désintégrations B-> D*K auprès de l'expérience BaBar. Physique des Hautes Energies - Expérience [hep-ex]. Ecole Polytechnique X, 2007. Français. ⟨tel-00201496⟩

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