Analysis of B [sigma] flavor oscillations at CDF

Abstract

The search for and the study of flavor oscillations in the neutral B,B, meson system is an experimentally challenging endeavor. This constitutes a flagship analysis of the Tevatron proton-antiproton collider physics program. In this dissertation we develop such an analysis of the time-dependent B, flavor oscillations using data collected with the CDF detector. The data samples are formed of both fully and partially reconstructed B meson decays, B, -+ D7r(irir) and B8 -- Dalv. 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+ and Bo mesons, which are further used for algorithm calibration and method validation. The B mesons lifetimes are extracted. The measurement of the Bo oscillation frequency yields Amd = 0.522 ± 0.017 ps-1. The search for B, 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 ED2 of 1.6%, to a data sample of 355 pb-1, a sensitivity of 13.0 ps-1 is achieved.

(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.