Search for pair-production of scalar leptoquarks decaying to electrons and quarks with the CMS detector using the full Run II dataset

Leptoquarks (LQs) are hypothetical particles which are present in several beyond-standard model theories. They would carry lepton number and baryon number, have fractional electric charge, and couple to both quarks and leptons. Here a search is presented for pair-produced scalar leptoquarks, with each leptoquark decaying into an electron and a quark, using the full Run II dataset collected by the CMS detector. LQ masses from 300 GeV to 3 TeV are considered in the analysis, in 100 GeV increments. Signal and backgrounds are modeled with MC simulation, except for the QCD multijet background, which is determined from data. The final event selection is made using a set of boosted decision tree classifiers to discriminate signal events from background, achieving better signal efficiency and background rejection than what is possible with a cut-based analysis. Upper limits on the LQ cross section are set for each mass hypothesis, and these are used to set a lower limit on the LQ mass. This analysis improves significantly on the previous CMS search for pair-produced LQs decaying to electrons and quarks, and it sets a comparable lower mass limit to the corresponding full Run II ATLAS result.