Search for new phenomena using the invariant mass distribution of same-flavour opposite-sign dilepton pairs in events with missing transverse momentum in√s =13 TeV ppcollisions with the ATLAS detector

aJUTS: s We thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently. We acknowledge the support of EPLANET, ERC, ERDF, FP7, Horizon 2020 and Marie Skłodowska-Curie Actions, European Union; MINECO, Spain AND CERCA Programme Generalitat de Catalunya.A search for new phenomena in final states containing an or pair, jets, and large missing transverse momentum is presented. This analysis makes use of proton-proton collision data with an integrated luminosity of , collected during 2015 and 2016 at a centre-of-mass energy with the ATLAS detector at the Large Hadron Collider. The search targets the pair production of supersymmetric coloured particles (squarks or gluinos) and their decays into final states containing an or pair and the lightest neutralino () via one of two next-to-lightest neutralino () decay mechanisms: , where the Z boson decays leptonically leading to a peak in the dilepton invariant mass distribution around the Z boson mass; and with no intermediate resonance, yielding a kinematic endpoint in the dilepton invariant mass spectrum. The data are found to be consistent with the Standard Model expectation. Results are interpreted using simplified models, and exclude gluinos and squarks with masses as large as 1.85 and 1.3 at 95% confidence level, respectively