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Mesure de l'amplitude de transition b en u et de la phase CKM gamma a l'aide des desintegrations B0 en D0K*0 reconstruites avec l'experience Babar

Abstract : In this thesis we present CP violation studies in the B mesons system, and in particular measurements of the angle gamma of the Unitarity Triangle, using data collected by the Babar experiment. The angle gamma is the relative weak phase between the Vub and Vcb elements of the CKM matrix. A crucial parameter, which drives the sensitivity to gamma, is the ratio r between b to u and b to c transition amplitudes.
In the first part of the thesis, general issues on gamma studies and the status of the present measurements are introduced.
The experimental work is then detailed. It is composed of two different analyses of B0 to D0(barD0K*0). In the first analysis, these decays are studied through the ADS method, where the neutral D mesons are reconstructed into K+pi-, K+pi-pi0 and K+pi-pi+pi- (and complex conjugate states).This analysis allows to determine, for the first time, the ratio r for B0 to D0K*0, which is found to be r = 0.260+0.077-0.088. The large value for the parameter r makes the use of this channel interesting for present and future facilities, for the determination of gamma.
In the second analysis, tha channel B0 to D0(barD0K*0) is studied with a Dalitz method and the neutral D mesons are reconstructed into KSpi+pi- final states. The determination of gamma from this analysis is gamma = (162 +- 56) deg, with a 180 deg ambiguity. The result for r from the combination of the two analyses is: r=0.259+0.073-0.079}. These results represent the first contraints on gamma and r obtained
from neutral B decays.
Finally, data driven simulation studies are discussed, which show that the study of the B0 to D0(barD0K*0) is competitive, for the determination of gamma, with the other analysis aiming to extract gamma from charged B decays.
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Contributor : Viola Sordini <>
Submitted on : Wednesday, July 16, 2008 - 3:24:54 PM
Last modification on : Friday, November 20, 2020 - 5:38:01 PM
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  • HAL Id : tel-00294721, version 2

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V. Sordini. Mesure de l'amplitude de transition b en u et de la phase CKM gamma a l'aide des desintegrations B0 en D0K*0 reconstruites avec l'experience Babar. Physique des Hautes Energies - Expérience [hep-ex]. Université Paris Sud - Paris XI, 2008. Français. ⟨tel-00294721v2⟩

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