Wuppertal 2015 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

T: Fachverband Teilchenphysik

T 5: Experimentelle Methoden: Tracking und Flavour-Tagging

T 5.5: Vortrag

Montag, 9. März 2015, 15:00–15:15, L.09.21 (HS 13)

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

Tau leptons often play an important role in searches for new physics. However, their small decay length 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 makes up 65% of all decays. The hadronic constituents in those decays 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. 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. Furthermore, the center of mass energy of the LHC will be increased and bunch spacing will be decreased. This requires a revision of the track selection criteria applied for hadronic tau decays used for run 1. Performance of the former track selection is presented as well as improvements with focus on improving efficiency to reconstruct the correct number of tracks for each hadronic tau decay. Furthermore, a new approach using multivariate techniques is presented, which attempts to obtain best separation of tracks from hadronic tau decays and tracks from pile-up, conversions, underlying event, etc. For this purpose correlations of track quality criteria as a function of the transverse momentum of the tau decay are also considered to account for conditions at different p_T regions.