Precision Measurements of Lifetime and $\bf CP$ Violation Phase in the $\bf B^{0}_{s}$ Meson with the DØ Detector

Abstract

The Standard Model of Partice Physics (SM) is probably the most successful theory, regarding to his predictions. The SM prediction for $CP$ violation is not enough to explain the overwhelming asymmetry among the matter and anti-matter abundance. Measuring some process where $CP$ violation is different to the one predicted by the SM would be a clear signal for Physics Beyond the Standard Model. The SM prediction for the $CP$ violation phase, $\phi_{s}$, in the $B^{0}_{s}$ meson is practically equal to zero for the current experiments. This means that measuring a deviation from zero in $\phi_{s}$ could be an indication for Physics Beyond the SM. On the other hand, the approximation based on the ``heavy quark symmetry'' let approximated calculations of the fundamental quantities of those hadrons containing a heavy quark, $c,b,t$. These calculations are expressed as expansions on inverse powers of the heavy quark mass in such hadron. This formalism is called `` Heavy Quark Effective Theory'' (HQET), and has been successful predicting some properties of the heavy hadrons. The HQET prediction for the lifetime ratio the $B^{0}_{d}$ and $B^{0}_{s}$ is practically equal to one. So, measuring with good precision the $B^{0}_{s}$ lifetime is also a way to test an approximation based on the SM. In this thesis it is detailed presented the method to measure the $\phi_{s}$ and the lifetime ratio of the $B^{0}_{d}$ and $B^{0}_{s}$, among other quantities, with the DØ located in the Fermi National Accelerator Laboratory, in the United States.