Enhancing ZH->llbb Searches With Multiple Interpretations in the ATLAS Detector

Abstract

This thesis presents an attempt at using multiple event interpretations to enhance the boosted decision tree used in the search for the Standard Model Higgs boson decay to the bb final state at a Higgs mass of 125 GeV with the ATLAS detector, looking in particular at the ZH->llbb process. Recent studies have suggested that using multiple event interpretations offered by constructing jets with different radii can offer a large improvement over the traditional deterministic approach to event interpretation. Monte Carlo datasets generated using a center of mass energy sqrt(s) = 13 TeV are used for this analysis, and the data's truth labels are used to evaluate the performance of the boosted decision tree. Using a S/sqrt(S+B) measure of significance for the boosted decision tree, improvements of 1.9% in the pTV < 120 GeV region and 6.5% in the pTV > 120 GeV region are found by using additional inputs derived from the multiple event interpretations, both of which are smaller than the expected improvements from previous work.