Search for supersymmetry in events with soft leptons, low jet multiplicity, and missing transverse energy in proton–proton collisions at √s=8TeV

Abstract

Resultsare presented from a search for supersymmetric particles in scenarios with small mass splittings. The data sample corresponds to 19.7fb−1of proton–proton collisions recorded by the CMS experiment at √s=8TeV. Thesearch targets top squark ( t) pair production in scenarios with mass differences m =m(t) −m( χ01)below the W-boson mass and with top-squark decays in the four-body mode (t→b ν χ01), where the neutralino ( χ01) is assumed to be the lightest supersymmetric particle (LSP). The signature includes a high transverse momentum (pT) jet associated with initial-state radiation, one or two low-pTleptons, and significant missing transverse energy. The event yields observed in data are consistent with the expected background contributions from standard model processes. Limits are set on the cross section for top squark pair production as a function of the tand LSP masses. Assuming a 100% branching fraction for the four-body decay mode, top-squark masses below 316GeV are excluded for m =25GeVat 95%CL. The dilepton data are also interpreted under the assumption of chargino–neutralino production, with subsequent decays to sleptons or sneutrinos. Assuming a difference between the common χ+1/ χ02mass and the LSP mass of 20GeV and a τ-enriched decay scenario, masses in the range m( χ+1) <307GeVare excluded at 95% CL.