| Leptoquarks are theoretical particles proposed by various extensions to the Standard Model of particle physics. They couple to both quarks and leptons, explaining the correspondence between the three generations of quarks and leptons in the Standard Model that are essential to ensure its renormalizability. Experimental constraints indicate that leptoquarks would only couple to a single generation, and this thesis describes searches performed with the CMS detector for leptoquarks of the first or second generation, produced singly and decaying to final states containing either two electrons and one jet or two muons and one jet.;The search is based on a data sample of proton-proton collisions at the LHC with center-of-mass energy √s = 8TeV recorded with the CMS detector and corresponding to an integrated luminosity of 19.6 fb-1. No signal-like excess is observed. Upper limits are set on leptoquark cross sections at the 95% confidence level via the CLS modified frequentist method. Single production of first-generation leptoquarks with a coupling lambda = 1 and branching fraction B(LQ → eq) = 1 is excluded for masses below 1755 GeV, and second-generation leptoquarks with a coupling lambda = 1 and branching fraction B(LQ → muq) = 1 is excluded for masses below 660 GeV. These lower limits on leptoquark mass are the most stringent limits for single production of leptoquarks to date. |
