Date of Award

5-2012

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Physics

Major Professor

Stefan M. Spanier

Committee Members

Marianne Breinig, George Siopsis, Robert Hinde

Abstract

The production of hadrons containing b-quarks has been measured in proton anti-proton collisions up to center-of-massenergies of 1.96 TeV at the Tevatron. Information at lower energy is provided by electron-positron collision experiments.The underlying theory of hadronic interactions is tuned to those data but cannot reliably predict reaction rates from first principlesfor higher energies. Therefore, it is important to test the extrapolations and optimize model parameters for the new energy regime at the LHC. The b-hadrons from proton-proton collisions are a major source of background in searches for the Higgs boson andother heavy not-yet-discovered particles. Hence, it is important to quantify their presence in different reactions for the main researchprogram at the LHC. The measurement of the Bs-meson production cross section presented in this dissertation complements the measurementsfor the B+ and the Bd mesons. The outcome is compared to different models for quark production and hadronization. The three CMS measurement of B-meson production cross sections are used to calculate the Bs to J/psi phi branching fraction. The measurement of the time-dependent decay rate of Bs mesons probes the weak interaction and includes the possibilityto observe sizable particle anti-particle asymmetries caused by heavy particles and new forces between them that are notpredicted by the Standard Model. In this dissertation the lifetime, lifetime difference, and CP-composition in the decay Bs to J/psi phihave been extracted with a Maximum Likelihood fit. The J/psi meson decays into two muons, while the phi meson into two charged kaons. The results are presented for the data recorded during the year 2010 with the Compact Muon Solenoid. It is a general-purpose particle detector centered at one of the interaction points of the Large Hadron Collider, a proton-proton collider located at the particle physics laboratory CERN in Geneva (Switzerland). It is designed to explore a wide range of physics in proton-proton collisions. The investigations presented here assess and benchmark the performance of a variety of detector components including track and muon reconstruction.For reconstruction of long-lived particles, such as the b-hadrons, the silicon pixel detector provides the most significant information.

Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS