Würzburg 2018 – scientific programme

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T: Fachverband Teilchenphysik

T 75: Suche nach Supersymmetrie III

T 75.6: Talk

Thursday, March 22, 2018, 17:45–18:00, Philo-HS3

Optimising the Sensitivity of the ATLAS Experiment for the Direct Pair-Production of Scalar Tau Leptons at the LHC in Run-2 — Ferdinand Krieter, •Clara Leitgeb, and Alexander Mann — Ludwig-Maximilians-Universität, München

Supersymmetry is a promising extension of the Standard Model of par- ticle physics. An important goal of the physics program of the ATLAS detector at the LHC is the search for direct pair-production of scalar tau leptons (staus) and their subsequent decay into a tau lepton and the lightest neutralino. Because of the very low expected cross section, a search for this process in the first run of the LHC could hardly reach any sensitivity. But the higher center-of-mass energy in run-2 results in a higher cross section for this process. Together with the enhanced integrated luminositiy in run-2, this causes an increase of the produc- tion rate of stau pairs. Furthermore, the identification efficiency of tau leptons has been improved in run-2. However, there is also an increase of the cross sections of some Standard Model background processes. In addition, the trigger selection becomes more difficult due to the higher instantaneous luminosity and pile-up.

In this talk, the search for direct stau production with ATLAS at a center-of-mass energy of 13 TeV will be presented. The main focus is on the design of an optimal signal region, for which a cut-and-count approach is used as well as boosted decision trees. In order to improve the statistical uncertainty on the contribution of events containing one W -boson and jets, a reweighting technique called tau promotion is applied.