利用噴流結構於8TeV質心能量尋找矢量T(2/3)夸克

Abstract

This thesis presents the search for pair-produced vector-like top quark partners of charge 2/3e in 19.7fb^-1 of proton-proton collisions at S^(1/2) = 8 TeV collected with the CMS detector in 2012 at the Large Hadron Collider. This search is optimized for the decay mode T to bW in the fully hadronic final state. Due to the large mass of the T quark, its decay products are significantly boosted, requiring the use of specialized jet substructure techniques. Selected events must have four jets, of which two are assigned to the hadronic W boson decay and the other one or two are consistent with the hadronization of a b quark. No excess of events above the expected standard model backgrounds is observed and limits are set on the T pair-production cross section. T quarks with masses below 705 GeV/c^2 are excluded at the 95% confidence level. Sensitivity measurement on the T to tZ and T to tH decays is also performed. The result of the statistical combination with similar searches performed at CMS is also presented as it provides the strongest limits on vector-like T quarks.