Search for the Rare Baryonic $B^+$ to proton anti-Lambda Decay with the LHCb Detector and Alignment of Pixel Detectors

This thesis presents the search for the Rare Baryonic $B^{+}\rightarrow p\overline{\Lambda}$ decay and the alignment of Pixel Detectors, such as the TimePix telescope and the VELO upgrade. Several software-based methods to find the spatial alignment of tracking detectors are introduced. A software package in which these methods are included is developed in this thesis. The methods are compared and the alignment of the TimePix3 telescope software is successfully performed. The performance of the spatial alignment of the telescope is discussed. The alignment procedure for the upgraded VELO detector is developed and studied on simulation data. The search for rare baryonic decay mode $B^{+}\rightarrow p\overline{\Lambda}$ is carried out using data taken by LHCb during its Run I in 2011 and 2012. The first evidence for this decay is reported with an, statistical only, significance of 4.14 $\sigma$. The branching fraction is measured to be $\mathcal B (B^+ \to p \bar {\Lambda}) = \left(2.41^{+0.76}_{-0.86}\left(stat.\right)\pm0.26\left(sys.\right)\right)\times10^{-7}$.