Search for supersymmetry with extremely compressed spectra with the ATLAS and CMS detectors

Results of searches for supersymmetry via direct production of third-generation squarks and gluinos are reported. The analysis use 20.3 fb${}^{-1}$ of proton-proton collision data recorded by the ATLAS experiment and 19.5 fb${}^{-1}$ recorded by the CMS experiment at a centre-of-mass energy of $\sqrt{s}$=8 TeV. Different signal regions based on monojet-like and c-tagged event selections optimize the sensitivity for direct top squark pair production with small mass differences between the hypothetical supersymmetric particles. %across the top squark--neutralino mass parameter space. In an complementary approach, the heavier top squark is searched for under the assumption that a Z boson is emitted in its decay to the lighter top squark. This strategy retains sensitivity for mass configurations where signals of direct production of the lighter top squark are hard to distinguish from the top quark pair production background. For the case of the gluino, a soft lepton analysis improves sensitivity for small mass differences between the gluino and the lightest neutralino. No significant excess above the Standard Model background expectation is observed in any of the analyses. The resulting limits significantly extend previous results at colliders.