Master Thesis Open Access
Pfeffer, Emanuel
<?xml version='1.0' encoding='utf-8'?> <oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd"> <dc:creator>Pfeffer, Emanuel</dc:creator> <dc:date>2021-01-12</dc:date> <dc:description>In this thesis, the interplay of two elementary particles of the SM, the two heaviest quarks top (t) and bottom (b), is studied in detail. Processes in which a top quark-antiquark pair occurs in associated production with two bottom quarks (tt+bb) play an important role in particle physics. The two quarks show a high mass difference and their associated production is therefore particularly difficult to model, accompanied by large uncertainties [6]. In addition, events involving this process constitute a large irreducible background in measurements of tt+H production in H → bb decays. These measurements are an essential test of the SM and an important constraint of physics beyond the SM. Consequently, the tt+bb process needs to be thoroughly understood. Events comprising tt+bb processes are analyzed at two different Monte Carlo event simulation levels in this thesis. The first part compares different existing event simulations used at the CMS experiment for the tt+bb process in the single-lepton channel and investigates possible differences in the modeling. The analysis is technically realized in a way that allows a direct comparison of the simulations with those of the ATLAS experiment. The comparison of simulations of both experiments is performed building on this analysis. This enables the design of a common strategy between ATLAS and CMS. The second part focuses on strategies for assigning b jets to their origin. Since top quarks decay into b quarks almost exclusively, the final state of an event involving the tt+bb process usually consists of four or more b jets. However, it is unknown in the event reconstruction which b jets result from top quark decays and which originate from additional gluon radiation and subsequent splittings into pairs of b quarks in the event.</dc:description> <dc:identifier>https://publish.etp.kit.edu/record/22082</dc:identifier> <dc:identifier>oai:publish.etp.kit.edu:22082</dc:identifier> <dc:language>eng</dc:language> <dc:relation>url:https://publish.etp.kit.edu/communities/cms</dc:relation> <dc:relation>url:https://publish.etp.kit.edu/communities/etp</dc:relation> <dc:rights>info:eu-repo/semantics/openAccess</dc:rights> <dc:subject>CERN</dc:subject> <dc:subject>CMS</dc:subject> <dc:subject>Experiment</dc:subject> <dc:subject>Monte Carlo Simulation</dc:subject> <dc:subject>Machine Learning</dc:subject> <dc:subject>Artificial Intelligence</dc:subject> <dc:subject>Deep Neural Networks</dc:subject> <dc:subject>tt+bb</dc:subject> <dc:subject>top</dc:subject> <dc:title>Studies on tt+bb production at the CMS experiment</dc:title> <dc:type>info:eu-repo/semantics/masterThesis</dc:type> <dc:type>thesis-master-thesis</dc:type> </oai_dc:dc>