Level-1 jet trigger studies for the CMS experiment

The Compact Muon Solenoid (CMS) detector is introduced, with particular emphasis on the calorimeters, and the trigger and data acquisition system. An FPGA-based sort processor for use in the CMS Global Calorimeter Trigger has been designed. The algorithm used and its implementation are described, together with results from a demonstrator board built to test the design. Further successful results from a second, more sophisticated prototype processor board are also described. The Level-1 jet trigger rate and performance have been calculated using detailed simulation programs. The results are presented for low LHC luminosity running conditions. The trigger segmentation of the very forward calorimeters has been investigated. The results show that a proposed extension of the baseline segmentation (increasing the number of towers in pseudorapidity from four to six), while offering slightly improved performance, does not provide sufficient increase to warrant the change. Finally, a simple di-jet trigger can be extended using cuts on the separation of the two jets in pseudorapidity. The performance of such a trigger in selecting weak boson fusion events is found to be insufficient to be of general use. However, excellent trigger efficiency for an invisibly decaying light Higgs boson can be provided by requiring two tag jets, well separated in pseudorapidity, together with missing transverse energy above a threshold of 60 GeV.