Search for supersymmetry in the single lepton final state in 13 TeV pp collisions with the CMS experiment

Abstract

Supersymmetry is among the most promising theories of physics beyond the Standard Model, but until now any direct evidence in its support is still missing. A search for events with a single charged lepton in the final state, coming from supersymmetric processes, is performed using proton-proton collision data taken by the CMS experiment at the CERN LHC in the 2015 run with a center of mass energy of 13 TeV. The integrated luminosity of the dataset corresponds to 2.3fb-1. The signal model describes gluino pair production with masses in the TeV range. The cascade decay of each gluino involves production of 1st and 2nd generation quark jets and a neutral stable supersymmetric particle in the final state, the lightest neutralino, which provides a significant amount of missing transverse energy. Exactly one charged lepton is required in the final state, which comes from the decay of one of the involved W bosons. At the same time, multijet events are highly suppressed by this requirement. The other W boson will decay hadronically. After applying a baseline selection to suppress the bulk of background events, the re- maining events are split into a few signal regions with different kinematic requirements. A robust method to estimate background events from Standard Model processes using control samples in data is then introduced. This method is validated both in simu- lated samples and in data. Systematic uncertainties of the background prediction and simulated signal samples are studied. The observation in the signal regions is in good agreement with the expectation from the Standard Model. Therefore, exclusion limits on gluino and neutralino masses of the tested model are set. Gluinos with masses up to 1400 GeV and neutralinos up to 850 GeV are excluded with 95% confidence level in the considered model, improving previous mass limits by several hundred GeVs.