Measurement of forward-backward asymmetry and search for new physics in the dielectron channel with the ATLAS detector

High pT , isolated electrons are key components of some of the most interesting signatures that may be observed in collision data from the Large Hadron Collider (LHC). One such example is the decay of a high mass, neutral particle with narrow natural width to an e+e− pair. This thesis outlines the author’s contributions to the direct, model independent search for such a particle as a bump in the dielectron invariant mass spectrum using 167 pb−1 of data collected by the ATLAS detector in 2011. Limits on such a resonance in the context of an extra heavy gauge boson (Z’) have been set. Additionally, the electron forward-backward charge asymmetry, which is also sensitive to the presence of a Z’ particle, is measured as a function of invariant mass with 1.073 fb−1 proton-proton collision data recorded by the ATLAS experiment. The observed distribution is compared to the Standard Model expectation using simulated data in order to search for evidence of a Z’. In both cases, no evidence for a Z’ is observed. Different amounts of data for the two analyses correspond to the fact that the indirect search was performed several months after the direct one.