Title: Eﬀective Field Theory Interpretation of ATLAS Top Quark Measurements
Abstract: In the ﬁrst part of this dissertation, the combination of ATLAS top quark measurements to constrain dimension-six operator coeﬃcients is presented. Top quark measurements provide a powerful tool to constrain the electroweak interaction of top quarks. Many models of physics Beyond the Standard Model (BSM) predict deviations of top quark interactions from the Standard Model. The Standard Model Eﬀective Theory (SMEFT) provides a framework to parameterize BSM eﬀects in a model independent way. Combining top quark measurements allows to constrain several Wilson coeﬃcients of the dimension-six SMEFT operators at once. Speciﬁcally, the combination of the √s = 8 TeV t-channel single top cross section, the W helicity fractions and the single top decay distributions is studied. This allows to constrain a set of ﬁve Wilson coeﬃcients, four of which generate modiﬁcations to the W tb interaction vertex and one four-quark operator. Systematic uncertainties are correlated between the measurements and these correlations are calculated and included in the combination. Limits are set simultaneously on all Wilson coeﬃcients as well as individually. All limits are in accordance with Standard Model predictions.
In the second part, the new ATLAS 3D event display VP1-Light is presented. VP1-Light is a lightweight, standalone version of the general purpose 3D event display VP1. VP1 is tightly integrated into the ATLAS experiment’s software framework, making the use of VP1 rather restrictive. With VP1-Light these restrictions have been eliminated giving ATLAS physics analysis users an easy to use event display.
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