A Selection Framework for LHCb’s Upgrade Trigger

The LHCb experiment at the Large Hadron Collider at CERN is planning a major detector upgrade for the next data taking period. The instantaneous luminosity is increased by a factor of five to generate more data per time. The hardware trigger stage preceding detector readout is removed and LHCb now has to process 30 MHz of incoming events in real time. The work presented in this thesis shows three contributions towards a fast and efficient trigger system. The first contribution is a multi-threaded scheduling algorithm to work with negligible overhead in the Upgrade regime. It is the first implementation for LHCb capable of realizing arbitrary control and data flow at the required speed. It restricts itself to inter-event concurrency to avoid costly runtime scheduling decisions. The second contribution comprises several algorithms to perform particle combi- nation, vertexing and selection steps in the second HLT stage. These algorithms show competitive performances which can speed up the selection stage of HLT2 by orders of magnitude. Employing these algorithms marks a significant step towards an HLT2 application fast enough for the increased event rate. The third contribution concerns the most important and most costly HLT2 selection at LHCb, the Topological Trigger. It aims to inclusively capture many beauty-flavored decay chains. First, the algorithm for event selection is optimized. In a second step, output bandwidth is reduced significantly by employing a classification algorithm for selecting additional relevant information present in the event.