ATLAS High-Level Trigger Algorithms for Run-2 Data Taking

Following the successful Run-1 LHC data-taking, the long shutdown gave the opportunity for significant improvements in the ATLAS trigger capabilities, as a result of the introduction of new or improved Level-1 trigger hardware and significant restructuring of the DAQ infrastructure. To make use of these new capabilities, the High-Level trigger (HLT) software has been to a large extent rewritten, introducing in its turn a plethora of new features and improved algorithms for object reconstruction. The HLT algorithms rely heavily on the offline reconstruction algorithms with the aim to have an even larger efficiency for accepted events than in Run-1. A summary of the HLT algorithms for object reconstruction will be given with the focus on new and improved algorithms together with an outline of the strategy to combine them into a trigger menu. In addition, we will show examples of impressive code speedups and the expected trigger performance for Run-2 data-taking.