Münster 2017 – scientific programme

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T: Fachverband Teilchenphysik

T 111: Experimentelle Methoden 4 (Rekonstruktion)

T 111.4: Talk

Thursday, March 30, 2017, 17:30–17:45, JUR 253

A new energy reconstruction of hadronic Tau Leptons using at ATLAS — •Tobias Klingl, Peter Wagner, Philip Bechtle, and Klaus Desch — Universität Bonn

Final states with hadronically decaying tau leptons play an important role in many measurements and searches of the ATLAS Collaboration already during Run 1 of the Large Hadron Collider. With the discovery of the Higgs boson, one of the crucial measurements in Run 2 will be the Higgs CP mixing angle via spin effects in H→ ττ. This requires a good discrimination between the number of charged and neutral pions in the τ decay. The Run 1 reconstruction, however, solely differentiates tau decay modes by the number of charged pions, using calorimeter information only. To this end, the Run 2 reconstruction identifies charged pions by their tracks in the tracking system while using energy deposits in the calorimeter to reconstruct neutral pions. For energies below E≈ 140 GeV the good momentum resolution of the tracker yield to very good energy resolution of the new reconstruction. However, for energies rising above this threshold the calorimeter-based resolution improves over degrading track resolution. To achieve a smooth transition from the new reconstruction (low energies) to the Run 1 reconstruction (high energies) the corresponding energies are weighted by their respective core E_T resolutions after calibrating the mean of both distributions to zero. To handle non-Gaussian tails in the new reconstruction the Run 1 E_T is picked if the two reconstructed energy values are incompatible to each another.