Please use this identifier to cite or link to this item: http://arks.princeton.edu/ark:/88435/dsp015999n6456
 Title: A Search for Scalar Top Quarks in Final States with High Jet Multiplicity and a Lepton with the CMS detector at the Large Hadron Collider Authors: Mei, Kelvin Advisors: Tully, Christopher Contributors: Physics Department Subjects: Particle physics Issue Date: 2020 Publisher: Princeton, NJ : Princeton University Abstract: A search is conducted for scalar top quarks decaying in the Full Run II dataset for the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) of 137.2 fb−1 collected at a center of mass energy of √ s = 13 TeV. The particular models being investigated involve pair production of scalar top quarks decaying either through an R-parity violating coupling or through a stealth sector into high jet multiplicity ﬁnal states with low missing transverse energy. Novel machine-learning techniques have been applied, including gradient reversal, to extend sensitivity to a previously inaccessible and unexplored region of phase space. The highest observed local signiﬁcance for the signal models investigated is 2.78 for the R-parity violating SUSY model where the scalar top quark mass is 400 GeV, with a local p value at 2.7 × 10 −3 and a signal strength of 0.21 ± 0.07 times the theoretical predicated cross section. Limits are set at the 95% conﬁdence level for the R-parity violating models with the scalar top quark mass less than 675 GeV and for stealth SUSY models with the scalar top quark mass less than 975 GeV. URI: http://arks.princeton.edu/ark:/88435/dsp015999n6456 Alternate format: The Mudd Manuscript Library retains one bound copy of each dissertation. Search for these copies in the library's main catalog: catalog.princeton.edu Type of Material: Academic dissertations (Ph.D.) Language: en Appears in Collections: Physics

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