Hamburg 2016 – scientific programme

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T: Fachverband Teilchenphysik

T 74: Experimentelle Methoden II

T 74.4: Talk

Wednesday, March 2, 2016, 17:30–17:45, VMP8 SR 105

Track reconstruction in hadronic tau decays — •Dirk Duschinger, Arno Straessner, and Wolfgang Mader — IKTP, TU Dresden

Tau leptons often play an important role in searches for new physics. Not only because the Higgs decay probability into two tau leptons is of magnitudes larger than that for decays into muons and electrons, but also physics beyond the standard model can introduce enhanced couplings to tau leptons. However, the small decay length of 87µ m makes it hard to detect tau leptons directly. In fact, tau decays in the ATLAS detector at the LHC often take place before any detector component. The decay of taus into hadrons and an additional neutrino makes up 65% of all decays. The correct classification of hadronic tau decay products plays a crucial role in ATLAS tau reconstruction in terms of rejection against QCD jets and electrons. This relies on the correct selection of charged particles.

Several changes have been applied to the ATLAS detector during the first long shutdown phase of the LHC. This requires a revision of the track selection criteria applied for hadronic tau decays used for the first run of the LHC. Performance of the former track selection is presented as well as a new approach using multivariate techniques is presented. The focus is set on improving efficiency to reconstruct the correct number of tracks for each hadronic tau decay. For this purpose correlations of track quality criteria as a function of the transverse momentum of the tau are also considered to account for conditions at different p_T regions.