Abstract
Two searches for supersymmetric particles in final states containing a same-flavour opposite-sign lepton pair, jets and large missing transverse momentum are presented. The proton–proton collision data used in these searches were collected at a centre-of-mass energy sqrt{s}=8 TeV by the ATLAS detector at the Large Hadron Collider and corresponds to an integrated luminosity of 20.3 fb^{-1}. Two leptonic production mechanisms are considered: decays of squarks and gluinos with Z bosons in the final state, resulting in a peak in the dilepton invariant mass distribution around the Z-boson mass; and decays of neutralinos (e.g. tilde{chi }^{0}_{2} rightarrow ell ^{+}ell ^{-}tilde{chi }^{0}_{1}), resulting in a kinematic endpoint in the dilepton invariant mass distribution. For the former, an excess of events above the expected Standard Model background is observed, with a significance of three standard deviations. In the latter case, the data are well-described by the expected Standard Model background. The results from each channel are interpreted in the context of several supersymmetric models involving the production of squarks and gluinos.
Highlights
Supersymmetry (SUSY) [1,2,3,4,5,6,7,8,9] is an extension to the Standard Model (SM) that introduces supersymmetric particles, which differ by half a unit of spin from their SM partners
Previous searches for physics beyond the Standard Model (BSM) in the Z + jets + ETmiss final state have been performed by the CMS Collaboration [23,24]
At L2, only the regions of interest in η–φ identified at L1 are scrutinised, whereas complete event information from all detector sub-systems is available at the event filter (EF)
Summary
Supersymmetry (SUSY) [1,2,3,4,5,6,7,8,9] is an extension to the Standard Model (SM) that introduces supersymmetric particles (sparticles), which differ by half a unit of spin from their SM partners. Only weakly interacting, it escapes detection, leading to missing transverse momentum (pmT iss and its magnitude ETmiss) in the final state. In this scenario, the LSP is a darkmatter candidate [20,21]. A search for events with a SFOS lepton pair consistent with originating from the decay of a Z boson (on-Z search) targets SUSY models with Z boson production. J. C (2015) 75:318 a SFOS lepton pair inconsistent with Z boson decay (off-Z search) targets the decay χ20 → + −χ10. Previous searches for physics beyond the Standard Model (BSM) in the Z + jets + ETmiss final state have been performed by the CMS Collaboration [23,24]. ATLAS [26] dataset at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 20.3 fb−1
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