Electron Identification at CMS detector using LHC data

Abstract

The Standard Model of particle physics is extremely well tested and yet is not believed to be a theory of everything. Many extensions of the Standard Model predict the existence of new particles. The Large Hadron Collider (LHC) is a high energy proton-proton collider which may be able to produce such particles. In this work strategies have been developed to search for new physics by identifying high energy electrons produced by the decay of W boson using 2.8 pb-1 of real data. The electron identification for CMS has been presented. Simple cut based selections and a complete set of variables to distinguish between real electrons and background electrons are described. The detection of electrons is of particular importance at LHC as these particles intervene in the flagship H -> ZZ* -> 4e and H -> WW* -> 2e2v channels for the search of the Standard Model (SM) Higgs. Electrons are also important in many SUSY scenarios as produced in the leptonic decays of charginos and neutralinos. Electrons also appears in searches for TeV resonances that may come from new symmetries or as consequences of scenarios involving extra spatial dimensions. Last but not the least, electrons appear in the final state of many Standard Model processes involving top quarks or electroweak bosons, that constitute backgrounds to new signals or are intended to be used as calibration processes. In second part of my thesis background sources for electrons coming from W bosons have been studied. Electron identification variables are plotted in different regions of background, to study the background as deeply as possible. This work has been done for the first time using LHC's real data.