ATLAS muon trigger performance

Muons in the final state represent an important signature for many physics studies performed at the Large Hadron Collider (LHC), involving analyses on Standard Model measurements and on new physics searches. An optimized selection of such events requires an efficient and deeply understood muon trigger system. The present work describes the ATLAS muon trigger, consisting of a hardware-based system (Level-1) followed by a software-based reconstruction (High-Level Trigger). To handle the increase of luminosity in Run 2, several upgrades have been implemented to reduce the trigger rate, while still maintaining high values for the efficiency. Such improvements include the request of a coincidence of hits in the muon spectrometer and the hadronic tile calorimeter, an optimised muon isolation and a better estimation of transverse momentum. An overview will be presented on the most recent improvements of the ATLAS muon trigger and on its performance during Run 2. Finally an outlook for the most relevant upgrades planned for Run 3 will be reported.