A Search for First Generation Leptoquarks in s^1/2 = 7 TeV pp Collisions with the ATLAS Detector

Abstract

The Standard Model is an incomplete theory of nature. Numerous extensions of the Standard Model predict the existence of leptoquarks (LQ), color-triplet bosons which carry both baryon and lepton number. This dissertation presents the results of a search for pair production of first generation scalar leptoquarks in the eMETjj final state. The search is performed in pp collisions corresponding to an integrated luminosity of 1.03 fb^-1, at a center-of-mass energy s^1/2 = 7 TeV, recorded with the ATLAS detector at the LHC. A multivariate discriminant is used to distinguish signal-like events from background-like events. Observations are consistent with expectations from Standard Model backgrounds, thus limits on allowed LQ mass are determined. First generation scalar leptoquarks with mass m < 558 GeV are excluded at a 95% confidence level for Β = BR(LQ % → eq) = 0.5. When combined with a complimentary search in the eejj final state, leptoquarks with mass m < 607 (660) GeV are excluded for Β = 0.5 (1.0). These are the strongest limits in existence.