Optimization of Flavour Tagging Algorithms for the LHCb Experiment

Studies of $C\!P$ violation can be used to test the Standard Model and might give insight into New Physics. Therefore, a wide range of $C\!P$ measurements, including time-dependent decay rate measurements, are performed with the LHCb Experiment. Many of these are subject to mixing of neutral $B$ meson states with their antiparticles. The knowledge of the initial $B$ flavour is essential in these cases which is why several Flavour Tagging algorithms are used to deduce this information from the available event properties. These algorithms must be adjusted to changes in the shape of the event properties, resulting from an upgrade of the LHC centre-of-mass energy to $\sqrt{s} = 13\,\mathrm{TeV}$. To simplify this process, the Flavour Tagging software is re-implemented. The tagging power of the muon, electron and kaon tagger is measured based on $B^+ \to J\!/\!\psi K^+$ data, which is processed within the new framework. It is found to be $(0.782 ± 0.018)\%$, $(0.243 ± 0.011)\%$ and $(0.649 ± 0.020)\%$ for Run 1 data, respectively, and $(0.67 ± 0.05)\%$, $(0.134 ± 0.019)\%$ and $(0.54 ± 0.04)\%$ for Run 2 data. Furthermore a new inclusive strategy for the muon tagger is implemented that improves its tagging power to $\varepsilon_\text{eff} = (1.09 ± 0.04)\%$ on Run 1 data and $\varepsilon_\text{eff} = (0.83 ± 0.06)\%$ on Run 2 data.