Performance of the ATLAS Tau Trigger in Run 2

Abstract

Tau leptons are used in a range of important ATLAS physics analyses, including searches for SM Higgs boson decays to fermions and measurements of the Higgs-fermion couplings, searches for Higgs boson partners, and heavy resonances that decay into pairs of tau leptons. Events for analyses are provided by a number of single and di-tau triggers, as well as triggers requiring tau leptons in combination with other objects. As the luminosity of proton--proton collisions at the LHC is going to exceed the design value of $10^{34} \mathrm{cm}^{-2}\mathrm{s}^{-1}$ in Run 2, the tau trigger strategies have become more sophisticated than in Run 1. Topological selections at the first trigger level, fast tracking algorithms and improved identification requirements are the main developments to allow a large program of physics analyses with tau leptons. The performance of the ATLAS tau trigger during the 2015 and early 2016 data taking is discussed, as well as plans for further developments envisaged during Run 2.