Muon Strategies for the High Level Trigger of the LHCb Experiment

The LHCb experiment is devoted to a rich Flavour Physics program, analysing the proton-proton collisions provided by the LHC. The first stage of separation between signal and background is performed by the trigger system, a set of algorithms which, under tight timing constraints and with limited access to the detector information, produce a decision on whether to record each particular collision event. Due to the importance of decays containing muons in the final state for the LHCb program, specialized trigger lines have been implemented, with the purpose of efficiently selecting these channels. This thesis presents the results of the work carried out before the LHC start-up, in the design and optimization of muon lines for the High Level Trigger, which was based on simulated events. The expected trigger performance is discussed for a variety of luminosity and bandwidth scenarios, considering key muonic decay processes. Next, this thesis describes the commissioning of the muon trigger lines using the first available data. The performance of the trigger selections under study was found, in general, to be in good agreement with MC predictions. High efficiencies were measured in data, anticipating an excellent trigger performance for key decays such as $B_s \to \mu^{+}\mu^{-}$.