Search for Pair Production of Third-Generation Scalar Leptoquarks and R-Parity Violating Top Squarks in Proton-Proton Collisions at sqrt(s) = 8 TeV

Abstract

This dissertation presents a search for pair production of third-generation scalar leptoquarks or top squarks in R-parity violating supersymmetry decaying through the coupling λ′₃₃₃, with the new scalar particle decaying to a tau lepton and a bottom quark. The data used in this search were collected by the Compact Muon Solenoid experiment and comprise 19.7 fb^-1 of proton-proton collision data from the Large Hadron Collider at a center-of-mass energy of √(s) = 8 TeV. No excess of events above the standard model background prediction is observed. The existence of third-generation scalar leptoquarks or top squarks with masses below 740 GeV is excluded at the 95% confidence level, assuming the branching fraction for the decay to a tau lepton and a bottom quark is 100%. This is currently the strongest limit on this kind of leptoquark or top squark. The search is extended to address a chargino-mediated decay of the top squark involving the R-parity violating coupling λ′_3jk, producing a tau lepton, a bottom quark, and two light quarks. The existence of top squarks in this model with masses below 580 GeV is excluded at the 95% confidence level. This is the first search for the pair production of top squarks with the decay involving the R-parity violating coupling λ′_3jk.