Search for supersymmetry in events with four or more leptons ins=8  TeVppcollisions with the ATLAS detector

Abstract

Results from a search for supersymmetry in events with four or more leptons including electrons, muons and taus are presented. The analysis uses a data sample corresponding to 20.3 fb −1 of proton-proton collisions delivered by the Large Hadron Collider at ffiffi ffi s p ¼ 8 TeV and recorded by the ATLAS detector.Signal regions are designed to target supersymmetric scenarios that can be either enriched in or depleted of events involving the production of a Z boson. No significant deviations are observed in data from standard model predictions and results are used to set upper limits on the event yields from processes beyond the standard model. Exclusion limits at the 95% confidence level on the masses of relevant supersymmetric particles are obtained. In R-parity-violating simplified models with decays of the lightest supersymmetric particle to electrons and muons, limits of 1350 and 750 GeV are placed on gluino and chargino masses, respectively. In R-parity-conserving simplified models with heavy neutralinos decaying to a massless lightest supersymmetric particle, heavy neutralino masses up to 620 GeV are excluded. Limits are also placed on other supersymmetric scenarios.

Search for the electroweak production of supersymmetric particles ins=8 TeVppcollisions with the ATLAS detector

“…Previous ATLAS searches for EW SUSY production [19][20][21][22][23] are combined with the new analyses presented in Secs. VII-IX.…”

“…The direct production of charginos, neutralinos, and sleptons (l) through electroweak (EW) interactions may dominate the SUSY production at the Large Hadron Collider (LHC) if the masses of the gluinos and squarks are large. Previous searches for electroweak SUSY production at ATLAS targeted the production ofl þl− ,τ þτ− ,χ þ 1χ − 1 (decaying throughl or W bosons),χ AE 1χ 0 2 (decaying throughl or W and Z=h bosons), andχ 0 2χ 0 3 (decaying throughl or Z bosons) [19][20][21][22][23], and found no significant excess beyond SM expectations. These searches are typically sensitive to scenarios where there is a relatively large Oðm W;Z Þ splitting between the produced sparticles and the LSP, leaving uncovered territory for smaller mass splittings.…”

“…[20] and four-lepton analysis in Ref. [21] is used to set limits oñ χ 0 2χ 0 3 production withl R -mediated decays, where the slepton mass is varied between theχ 0 2 andχ 0 1 masses. Scenarios where the slepton mass is 5%, 25%, 50%, 75%, and 95% of theχ 0 2 mass are studied for a masslessχ 0 1 , and the limits are shown in Fig.…”

“…A series of new analyses targeting regions in parameter space not covered by previous ATLAS analyses [19][20][21][22][23] are presented. The results from new and published searches are combined and reinterpreted to provide the final 8 TeV ATLAS limits on the production of EW SUSY particles in a variety of models.…”

“…The dependence of the limits on the mass of the intermediate slepton in models of electroweakino production withl-mediated decays is also studied, thus generalizing the results of Refs. [19][20][21]. In cases where the LSP is wino or higgsino dominated, the lighter electroweakino statesχ AE 1 ,χ 0 2 can have mass differences with theχ 0 1 ranging from a few GeV to a few tens of GeV, depending on the values of the other parameters in the mixing matrix [24].…”