Performance and Improvements of the ATLAS Jet Trigger System

At the harsh conditions of the LHC, with proton bunches colliding every 50 ns and up to 40 pp interactions per bunch crossing, the ATLAS trigger system has to be flexible to maintaining an unbiased efficiency for a wide variety of physics studies while providing a fast rejection of non-interesting events. Jets are the most commonly produced objects at the LHC, essential for many physics measurements. The ATLAS jet trigger is the primary mean for selecting events with high pT jets and its good performance is fundamental to achieve the physics goals of ATLAS. In this paper, the challenges of the ATLAS Jet Trigger system, its original limitations and the new developments that were implemented to overcome them will be described. Performance results, including efficiency measurements and resolutions with respect to the offline reconstructed jets, will also be shown.