The search for flavor oscillations in the neutral Bs - B meson system constitutes a flagship analysis of the Tevatron proton-anti-proton collider physics program and an important probe for effects due to new physics beyond the Standard Model of particles and interactions. In particular, the precise measurement of a process such as Boscillations sets a strong constraint on the parameters of quark-flavor mixing in the Standard Model. This dissertation reports the analysis which, for the first time, observed B- Bs oscillations, using data collected with the CDF detector. The sub-percent precision of the measurement is also noteworthy. The data sample used for this analysis includes fully and partially reconstructed Bdecays: ... The focus of this thesis is the algorithm of same-side-kaon tagging which provides _-0 a large fraction of the flavor-tagging power available to this analysis of B- B8 oscillations. Flavor tagging consists in assessing whether a B, meson is creates as a B_--0 or a B, state, and constitutes an important ingredient in the analysis presented in this document. The algorithm which is here described combines particle identification information and kinematic characteristics of the Bevent in an artificial neural network to provide improved tagging power E'2 of about 4.0 - 4.8%, depending on the data sample to which the algorithm is applied. The search for B1 oscillations is performed using an amplitude method based on a frequency scanning procedure. Applying a neural network-based combination of lepton, kaon and jet charge opposite-side tagging algorithms, with a total tagging power of ED2 = 1.8%, and the same-side-kaon tagging algorithm to a data sample of 1 fb-1, a signal of B- B_ oscillations with a significance greater than 5 standard deviations is found ...

The search for and study of flavor oscillations in the neutral B{sub s}B{sub s} meson system is an experimentally challenging task. It constitutes a flagship analysis of the Tevatron physics program. In this dissertation, they develop an analysis of the time-dependent B{sub s} flavor oscillations using data collected with the CDF detector. The data samples are formed of both fully and partially reconstructed B meson decays: B{sub s} {yields} D{sub s}{pi}({pi}{pi}) and B{sub s} {yields} D{sub s}lv. A likelihood fitting framework is implemented and appropriate models and techniques developed for describing the mass, proper decay time, and flavor tagging characteristics of the data samples. The analysis is extended to samples of B{sup +} and B{sup 0} mesons, which are further used for algorithm calibration and method validation. The B mesons lifetimes are extracted. The measurement of the B{sup 0} oscillation frequency yields {Delta}m{sub d} = 0.522 {+-} 0.017 ps{sup -1}. The search for B{sub s} oscillations is performed using an amplitude method based on a frequency scanning procedure. Applying a combination of lepton and jet charge flavor tagging algorithms, with a total tagging power {epsilon}'D{sup 2} of 1.6%, to a data sample of 355 pb{sup -1}, a sensitivity of 13.0 ps{sup -1} is achieved. They develop a preliminary same side kaon tagging algorithm, which is found to provide a superior tagging power of about 4.0% for the B{sub s} meson species. A study of the dilution systematic uncertainties is not reported. From its application as is to the B{sub s} samples the sensitivity is significantly increased to about 18 ps{sup -1} and a hint of a signal is seen at about 175. ps{sup -1}. They demonstrate that the extension of the analysis to the increasing data samples with the inclusion of the same side tagging algorithm is capable of providing an observation of B{sub s} mixing beyond the standard model expectation. They show also that the improved knowledge of {Delta}m{sub s} has a considerable impact on constraining the CKM matrix elements.

(Cont.) In a preliminary study, we develop a same side kaon tagging algorithm, which is found to provide a superior tagging power, of about 4.0% for the B, meson species. An evaluation of the dilution systematic uncertainties is not reported but after including the algorithm as is in the analysis the sensistivity is significantly increased to about 18 ps-'. An indication of a B, oscillation signal is seen at a frequency of about 17.5 ps-1. We show that the extension of the analysis to the increasing data samples with the inclusion of the same side tagging algorithm is capable of providing an observation of B, mixing beyond the standard model expectation. We show also that the improved knowledge of Am, has a considerable impact on constraining the CKM matrix elements.

Over the past decades the current theoretical description, the Standard Model of elementary particle physics, was solidified by many measurements as the basic theory describing fundamental particles and their interactions. It is extremely successful in explaining the high-precision data collected by experiments so far. The Standard Model includes several intrinsic parameters which have to be measured in experiments. Independent analyses of different physical processes can constrain those parameters. By combining those measurements physicists might be sensitive to physics beyond the Standard Model. If they are inconsistent it allows to get a hint on the theory that might supersede the Standard Model. The goal of the analysis presented in this thesis is to measure some of these parameters in the B{sub s} meson system. The B{sub s} meson, consisting of an anti-b and s quark, is not a pure mass eigenstate, thus allowing a B{sub s} meson to oscillate into its antiparticle via weak interacting processes. This is a general feature of any neutral meson. The history of meson mixing measurements is more then 50 years old. It was first observed in the kaon system. The oscillation in the B{sub d} system was measured very precisely by the B factories, whereas the oscillation frequency of the Bs was measured with more than 5[sigma] significance last year by CDF and first evidence for mixing in the D0 system was presented only this year.

The eld of particle physics explores elementary constituents of matter and interactions between them. During the last century remarkable achievements were made in this eld - smaller and smaller objects could be resolved. In this sense, the research objects gradually shifted from molecules over atoms and nucleons to point-like particles, which are assumed to be elementary. Interactions between these constituents are mediated by four fundamental forces. Three of them are described by the Standard Model of Particle Physics. Judged by its ability to describe observations and its capability to make predictions, this model is extremely successful. According to the standard model the constituents of matter are quarks and leptons. Both groups consist of six di erent species, so called avours, which may appear as particle or anti-particle. Quarks never appear as free particles. Only bound states of quark and anti-quark, called mesons, and three quarks, called baryons, are observed. The proton, for example, is composed of two up (u) and one down (d) quark. The focal point of this thesis is the B$0\atop{s}$ meson. In a nutshell, the thesis at hand has two aims: the first one is to calibrate a tagger using B$0\atop{s}$ oscillations and the second one is to improve the result (equation 1.1) on the mixing frequency itself.

This book is devoted to the broad subject of flavor physics, embracing the question of what distinguishes one type of elementary particles from another. The articles range from the forefront of formal theory (treating the physics of extra dimensions) to details of particle detectors. Although special emphasis is placed on the physics of kaons, charmed and beauty particles, top quarks, and neutrinos, the articles also dealing with electroweak physics, quantum chromodynamics, supersymmetry, and dynamical electroweak symmetry breaking. Violations of fundamental symmetries such as time reversal invariance are discussed in the context of neutral kaons, beauty particles, electric dipole moments, and parity violation in atoms. The physics of the CabibboOCoKobayashiOCoMaskawa matrix and of quark masses are described in some detail, both from the standpoint of present and future experimental knowledge and from a more fundamental viewpoint, where physicists are still searching for the correct theory. Contents: The Electroweak Theory (C Quigg); CP Violation (L Wolfenstein); Precision Electroweak Physics (Y-K Kim); Kaon and Charm Physics: Theory (G Buchalla); Kaon Physics: Experiments (T Barker); The Status of Mixing in the Charm Sector (J P Cumalat); Basics of QCD Perturbation Theory (D E Soper); Lattice QCD and the CKM Matrix (T DeGrand); The Strong CP Problem (M Dine); A Bibliography of Atomic Parity Violation and Electric Dipole Moment Experiments (C E Wieman); The CKM Matrix and the Heavy Quark Expansion (A F Falk); CP Violation in B Decays (J L Rosner); Lectures on the Theory of Nonleptonic B Decays (M Neubert); Asymmetrical e Collisions (A Roodman); Pathological Science (S Stone); Top Physics (E H Simmons); Neutrino Mass, Mixing, and Oscillation (B Kayser); Flavor in Supersymmetry (H Murayama); Technicolor and Compositeness (R S Chivukula); Models of Fermion Masses (G G Ross); Physics of Extra Dimensions (J D Lykken). Readership: Graduate students, postdoctoral fellows and senior researchers in high energy physics."