Mixing and CP violation in the B$$0\atop{s}$$ meson system at CDF; Mélange et violation de CP dans le système des mésons B$$0\atop{s}$$ à CDF (in French)
- Univ. of Paris VI-VII (France)
The two analyses presented in the thesis, the B$$0\atop{s}$$ mixing analysis and the B$$0\atop{s}$$ → J/ψφ angular analysis, share most of the technical implementations and features. Thus, my choice was to pursue in parallel the common aspects of the analyses, avoiding, whenever possible, repetitions. Each Chapter is split in two parts, the first one dedicated to the B$$0\atop{s}$$ mixing analysis and the second one describing the angular analysis on the B$$0\atop{s}$$ → J/ψφ decay mode. They are organized as follows. In Chapter 1 we present the theoretical framework of the B$$0\atop{s}$$ neutral mesons system. After a general introduction on the Standard Model, we focus on the quantities which are relevant to the Δms measurement and the CP violation phenomena, underlying the details concerning the study of pseudo-scalar to vector vector decays, P → VV, which allow to carry out an angular analysis. A discussion on the implication of the measurements performed in the search of physics beyond the Standard Model is presented. The accelerator facilities and the CDF-II detector are reported in Chapter 2. While describing the detector, more emphasis is given to the components fundamental to perform B physics analyses at CDF. The Chapter 3 is focused on the reconstruction and selection of the data samples. The Chapter starts with a description of the on-line trigger requirements, according to the B$$0\atop{s}$$ sample considered, followed by the offline selection criteria implemented to reconstruct B$$0\atop{s}$$ semileptonic and hadronic decays, fully and partially reconstructed, for the B$$0\atop{s}$$ mixing analysis, as well as the B$$0\atop{s}$$ → J/ψφ decay mode for the angular analysis. The subsequent Chapter 4 is dedicated to the revision of the technical ingredients needed in the final analyses. The B$$0\atop{s}$$ mixing elements are firstly described. The methodology historically used in the oscillation searches, the 'amplitude scan', is here introduced together with the calibration of the proper-decay-time resolution and the flavor tagging algorithms, in particular a closer examination of the same-side tagger performances is given. The B$$0\atop{s}$$ → J/ψφ angular analysis elements description then follows, focusing on the performances and the eventual differences with respect to the B$$0\atop{s}$$ oscillation search. The final results of the analyses are obtained with the use of an un-binned likelihood fitting framework: Chapter 5 presents the general principles behind this methodology and a description of both the maximum likelihood fitters employed. Chapter 6 contains the conclusive results on the B$$0\atop{s}$$ analyses. They are presented in an historical fashion: the measurement of the B$$0\atop{s}$$ oscillation frequency is followed by the first flavor tagged ΔΓs and βs measurements. The impact and the constraints on the parameters of the flavor model is part of the discussion in the Chapter. As cross-check of the B$$0\atop{s}$$ angular analysis, the B$$0\atop{s}$$ → J/ψK*0 decay mode has been additionally studied. Its angular analysis shows a competitive sensitivity with the B factories in measuring the parameters which define the decay. Not only this contributes to enforce the reliability of the entire framework, but it constitutes an excellent result by itself. Thus, we devote the entire Chapter 7 to the sole discussion of the angular analysis of the B$$0\atop{s}$$ → J/ψK*0 decay mode.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), High Energy Physics (HEP)
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 1345656
- Report Number(s):
- FERMILAB-THESIS-2008-106; 1241615
- Country of Publication:
- United States
- Language:
- French
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