Abstract
A search for the electroweak production of charginos, neutralinos and sleptons decaying into final states involving two or three electrons or muons is presented. The analysis is based on 36.1 fb^{-1} of sqrt{s}=13 TeV proton–proton collisions recorded by the ATLAS detector at the Large Hadron Collider. Several scenarios based on simplified models are considered. These include the associated production of the next-to-lightest neutralino and the lightest chargino, followed by their decays into final states with leptons and the lightest neutralino via either sleptons or Standard Model gauge bosons; direct production of chargino pairs, which in turn decay into leptons and the lightest neutralino via intermediate sleptons; and slepton pair production, where each slepton decays directly into the lightest neutralino and a lepton. No significant deviations from the Standard Model expectation are observed and stringent limits at 95% confidence level are placed on the masses of relevant supersymmetric particles in each of these scenarios. For a massless lightest neutralino, masses up to 580 GeV are excluded for the associated production of the next-to-lightest neutralino and the lightest chargino, assuming gauge-boson mediated decays, whereas for slepton-pair production masses up to 500 GeV are excluded assuming three generations of mass-degenerate sleptons.
Highlights
Background estimation and validationThe Standard Model (SM) backgrounds can be classified into irreducible backgrounds with prompt leptons and genuine ETmiss from neutrinos, and reducible backgrounds that contain one or more “fake” or non-prompt (FNP) leptons or where experimental effects lead to significant “fake” ETmiss
This paper presents a set of searches for the electroweak production of charginos, neutralinos and sleptons decaying into final states with two or three electrons or muons using 36.1 fb−1 of proton–proton collisi√on data delivered by the Large Hadron Collider (LHC) at a centre-of-mass energy of s = 13 TeV√
The primary sources of systematic uncertainty are related to the jet energy scale (JES) and resolution (JER), theory uncertainties in the Monte Carlo (MC) modelling, the reweighting procedure applied to simulation to match the distribution of the number of reconstructed vertices observed in data, the systematic uncertainty considered in the non-prompt background estimation and the theoretical cross-section uncertainties
Summary
Proton collisions, a neutralino LSP would escape detection and lead to an excess of events with large missing transverse momentum above the expectations from SM processes, a characteristic that is exploited to search for SUSY signals in analyses presented in this paper. The direct production of charginos and neutralinos or slepton pairs can dominate SUSY production at the LHC if the masses of the gluinos and the squarks are significantly larger. With searches performed by the ATLAS [18] and CMS [19] experiments during LHC Run 2, the exclusion limits on coloured sparticle masses extend up to approximately 2 TeV [20,21,22], making electroweak production an increasingly important probe for SUSY signals at the LHC. This paper presents a set of searches for the electroweak production of charginos, neutralinos and sleptons decaying into final states with two or three electrons or muons using 36.1 fb−1 of proton–proton collisi√on data delivered by the LHC at a centre-of-mass energy of s = 13 TeV√.
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