The ATLAS Muon Trigger Performance in pp collisions

Events with muons in the final state are an important signature for many physics topics at Large Hadron Collider (LHC), for instance, searches for Higgs boson production or new phenomena, measurements on the standard model processes like top-quark, W , Z production. Thus, efficient trigger on muons in data taking and understanding its performance are crucial to perform these physics studies. At LHC high rejection power against large backgrounds, while maintaining high efficiency for rare signal events, is required already at such online trigger stage. The ATLAS experiment employs a multi-level trigger architecture that selects the events in three sequential steps of increasing complexity and accuracy to cope with this challenging task. This proceedings paper reports about efficiency and general performance of the ATLAS muon trigger in proton-proton collisions at √ s = 7 TeV in 2011 runs and also at √ s = 8 TeV in 2012 runs.