Search for electroweak production of supersymmetric particles in final states with two or three leptons at $$\sqrt{s}=13\hbox {TeV}$$ s = 13 TeV with the ATLAS detector

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 of 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.

Muon g − 2 vs LHC Run 2 in supersymmetric models

“…For NC/ZW analyses, four results obtained from Refs. [70], [72], [73], and [74] (from top to bottom) are considered.…”

“…resulting in the ZW + E T signature. The search results are reported by the CMS collaboration with dtL = 36 fb −1 [70] and the ATLAS collaboration with dtL = 36-139 fb −1 [72][73][74] with the assumptions Br( χ 0 2 → Z χ 0 1 ) = Br( χ ± 1 → W ± χ 0 1 ) = 1. We interpret the results similarly to Sec.…”

“…The latest bounds with dtL = 36 fb −1 are provided in Refs. [69,72], where a simplified model with branching ratios…”

“…By reinterpretation of the CMS result [69], we obtain upper bounds on the cross section for the model points with x = 0.05, 0.5, and 0.95, which are respectively drawn by the red dotted, red solid, and red dashed lines. Reinterpretation of the ATLAS result [72,76] provides upper bounds for x = 0.5 drawn by the blue solid lines. Each of the upper bounds is evaluated in two criteria and thus drawn by two lines; the lower line corresponds to the "standard" limit while the upper one is the conservative limit; see text for details.…”

Expanding the parameter space of natural supersymmetry

“…Chargino mass up to 1.1 TeV and a neutralino of mass ∼ 600 GeV have been ruled out [57]. As for tiny mass splittings, charginos and neutralinos of masses less than 200 GeV have been excluded [58,59]. Searches targetting mass splittings near the electroweak scale [60][61][62], where W and Z bosons are on their mass shell, have led ATLAS to exclude neutralinos and charginos up to 345 GeV while CMS pushed the limit to 475 GeV.…”