Search for supersymmetry in events containing a same-flavour opposite-sign dilepton pair, jets, and large missing transverse momentum in $\sqrt{s}=8$ TeV $pp$ collisions with the ATLAS detector

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. ${\tilde{\chi }}_2^0\to {\ell }^{+}{\ell }^{-}{\tilde{\chi }}_1^0$), 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 3 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.

47 pages plus author list (64 pages total), 13 figures, 18 tables, published in Eur. Phys. J. C75 (2015) 318, all figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/SUSY-2014-10/, v3 includes modifications described in the erratum that can be found at http://dx.doi.org/10.1140/epjc/s10052-015-3661-9

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