Title: Search for supersymmetry in the single lepton final state in 13 TeV pp collisions with the CMS experiment
Other Titles: Test der natürlichen Supersymmetrie im hochenergetischen Proton-Proton Run am LHC
Language: English
Authors: Asilar, Ece 
Qualification level: Doctoral
Advisor: Schieck, Jochen 
Issue Date: 2017
Number of Pages: 126
Qualification level: Doctoral
A search for Supersymmetry will be presented to turn one more stone in the quest of what is beyond the Standard Model. The search is performed in events with a single charged lepton, multiple jets, and missing transverse energy. The proton-proton collision data were recorded by the CMS experiment during the 2016 run of the LHC at a center-of-mass energy of 13 TeV. The integrated luminosity of the dataset corresponds to 35.9 fb−1. Although the search is model independent, a simplified model of gluino pair production with masses in the TeV range is used as an example. In the model, each of the gluinos decays to two light quarks and an intermediate chargino, with the latter decaying to a W boson and a neutralino. The neutralino is considered to be the stable lightest supersymmetric particle which results in substantial missing transverse energy in the final state. Only events with a single charged lepton, which can be an electron or a muon, are considered. This requirement provides a clean event topology as well as suppresses most of the multijet events. No b quark is expected in the final state of the targeted signal model. Therefore, in the event selection, a veto on b-tagged jets is included. The search uses a powerful discriminating variable to distinguish between background and signal events, and 28 exclusive signal regions are defined in different kinematic observables to enhance sensitivity to a range of different mass scenarios. The estimation of the Standard Model background yields in the signal regions is performed using data in the control regions. This methodology is verified using simulated samples and data in validation regions. Finally, systematic uncertainties related to the background prediction and simulated samples are determined. No significant deviation from the predicted Standard Model background is observed. Therefore, stringent upper limits on the cross section of the considered simplified model are set. As a result, gluino masses below 1.9 TeV are excluded for neutralino masses below 300 GeV with 95% confidence level.
Keywords: Teilchenphysik; Supersymmetrie; LHC
Particle Physics; Supersymmetry; LHC
URI: https://resolver.obvsg.at/urn:nbn:at:at-ubtuw:1-107607
Library ID: AC14539699
Organisation: E141 - Atominstitut 
Publication Type: Thesis
Appears in Collections:Thesis

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