Dresden 2013 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 36: Top-Quarks 4
T 36.9: Vortrag
Dienstag, 5. März 2013, 18:45–19:00, HSZ-02
New Method to Estimate W+jets Background in tt Events at the ATLAS Experiment — •Arwa Bannoura — Bergische Universität Wuppertal
W +4 jets is the major background process for the tt semi-leptonic channel and other processes. In this analysis a new data driven method to estimate the W+jets background process is introduced. The idea of the method is to use Z+jets events to model W+jets events. The production of W and Z bosons is similar and the mechanism of associated jet production. An algorithm was used to convert Z+jets to be similar to W+jets by scaling the momentum of the two leptons and using one lepton to model ETmiss. Observables are compared and chosen based on their separation power between W+jets and tt events and their similarity between W+jets and converted Z+jets events. A binned maximum-likelihood fit is done in a neural network output distribution to measure the rate of W+jets events.