The ATLAS Hadronic Tau Trigger

During the 2012 run, the Large Hadron Collider (LHC) reached instantaneous luminosities of nearly 1034 cm−2s−1 with bunch crossings occuring every 50 ns. In this difficult environment of several overlapping interactions per bunch crossing (pile-up), the trigger system of the ATLAS detector has the task of reducing the event rate from 20 MHz to a few hundred Hz while keeping the most interesting physics events. Being the heaviest of all leptons, the tau lepton plays an important role in many physics processes. The ability to trigger on events containing hadronically decaying taus is therefore of special interest. This paper summarizes the concept of the ATLAS tau trigger and the improvements made in 2012. Furthermore the performance of the triggers including efficiency and rate measurements are presented and an outlook towards future developments of the tau trigger algorithms is given.