The ATLAS Muon Trigger

Events containing muons in the final state are important for many physics analyses performed by the ATLAS experiment at the Large Hadron Collider. To collect such events, an efficient and well-understood muon trigger is required. The ATLAS muon trigger consists of a hardware-based and a software-based subsystem. In order to cope with the high luminosity and pileup conditions in Run 2, several improvements have been implemented to suppress the trigger rate while maintaining a high efficiency. Recent improvements include addition of layers in the coincidence of the muon spectrometer and optimisation of a muon trigger isolation requirement, among others. An overview of the algorithms deployed by the ATLAS muon trigger and its performance in 2018 data taking is presented.