Münster 2017 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 111: Experimentelle Methoden 4 (Rekonstruktion)

T 111.3: Vortrag

Donnerstag, 30. März 2017, 17:15–17:30, JUR 253

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

Tau leptons often play an important role in searches for new physics, not only because the Higgs decay probability into tau leptons is magnitudes larger than that for decays into muons or electrons, but also physics beyond the standard model can introduce enhanced couplings to tau leptons. However, their short lifetime 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 majority of that decays are those into hadrons and additional neutrinos, where the hadronic constituents are most often 1 or 3 charged pions plus additional neutral pions. The classification of hadronic tau decays plays a crucial role in ATLAS tau reconstruction in terms of rejection against QCD jets and electrons.

Several changes have been applied to the LHC and the ATLAS detector during the first long shutdown phase. This requires a revision of the track selection criteria applied for hadronic tau decays. Improvements of the track selection are presented with focus on the efficiency to reconstruct the correct number of tracks for each hadronic tau decay. By using multivariate techniques, attempts are to obtain best separation of tracks from hadronic tau decays and tracks from pile-up, conversions, underlying event, etc. For this purpose track quality criteria as a function of the transverse momentum of the tau decay are considered.