Abstract:
I study the scope of discovering vector-like leptons at the Large Hadron Collider. Unlike the Standard Model leptons, vector-like leptons are non-chiral. Many beyond the Standard Model theories like composite Higgs model, warped extra-dimensions, supersymmetry predict the existence of such leptons. I studied vector-like lepton model in a multilepton final state using an ATLAS 8 TeV search result. I exclude vector-like leptons with masses below 150-280 GeV depending on specific model parameters. I study the doublet model at center of mass energy of 13 TeV using a multilepton final state. I design signal regions to maximize signal to background ratio and I make predictions about the sensitivity of multilepton final state to the vector-like lepton model. Using the optimized signal region, I predict 95% CL
exclusion limit for a luminosity of 20 fb^{-1}. I excluded vector-like leptons in the doublet model having masses below 365 GeV.
