Bonn 2020 – scientific programme

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T: Fachverband Teilchenphysik

T 42: Experimental methods II

T 42.1: Talk

Tuesday, March 31, 2020, 17:00–17:15, L-4.001

Quark gluon tagging in dijet searches using only calorimeter-based event information with the ATLAS experiment — •Lisa Marie Baltes — Kirchhoff-Institute for Physics, University Heidelberg

The analysis of dijet events can give us important information about new possible models beyond the Standard Model such as dark matter. In some models the massive mediator can be observed as an excess in the invariant mass spectrum of the decay product. However, dijet searches at masses below 1 TeV are statistically limited by the bandwidth and storage limitations of the detector. The trigger-object-level analysis (TLA) allows the search for low-mass resonances down to an invariant mass of 450 GeV by recording and analysing only a part of the full event information. In our signal model, the massive mediator decays into two quarks, while the QCD background is dominated by gluon-gluon and quark-gluon final states. Therefore, tagging the flavour of the two final state jets can suppress the background compared to the signal. TLA only uses information about the online reconstructed jets and some jet structure variables based on calorimeter information and therefore no tracking information is available. In this talk, the results from different neural networks are discussed, including ROC curves and background rejection efficiencies.