CP-Violation in Beautiful-Strange Oscillations at LHCb

The LHCb experiment is an experiment based at the LHC in Geneva and is dedicated to the study of mesons containing bottom and charm quarks. One of the primary goals of the physics at LHCb is to measure $\mathcal{C}\mathcal{P}\text{-violating}$ effects which lead to a dominance of matter over anti-matter in the universe. This thesis presents the measurement of the $\mathcal{C}\mathcal{P}\text{-violating}$ phase $\phi_s$ which is one of the golden channels at LHCb. This phase is observed as the interference between mixing of $B^0_{s}\leftrightarrow \overline{B^0_{s}}$ and decay of $B_s^0\rightarrow J/\psi\,K^{+}K^{-}$. The results, based upon the 1.0$\,\text{fb}^{-1}$ dataset collected by LHCb during 2011, are: $\phi_{s}=0.07\pm0.09\pm0.01$ rad, $\Delta\Gamma_{s}=0.100\pm0.016\pm0.002$ ps$^{-1}$ $\Gamma_{s}=0.663\pm0.005\pm0.006$ ps$^{-1}$. This analysis is also able to measure the mixing parameter $\Delta m_s=17.71\pm0.10\pm0.01\,\text{ps}^{-1}$. To improve upon this measurement the $B_s^0\rightarrow J/\psi\,K^{+}K^{-}$ analysis is combined with the $B_s^0\rightarrow J/\psi\,\pi^{+}\pi^{-}$ decay channel to make the most accurate measurements to date of, $\phi_s=0.01\pm0.07\pm0.01\,\text{rad}, \Delta\Gamma_{s}=0.106\pm0.011\pm0.007\,\text{ps}^{-1}$ and $\Gamma_{s}=0.661\pm0.004\pm0.006\,\text{ps}^{-1}$. As an integral part of this work a comprehensive software suite known as RapidFit was developed, which is used by many other physicists and this is described.