Search for direct top squark pair production in final states with one isolated lepton, jets, and missing transverse momentum in sqrt(s) = 8 TeV pp collisions using 13.0 ifb of ATLAS data

A search is presented for direct top squark pair production in final states with one isolated electron or muon, jets, and missing transverse momentum in proton-proton collisions at a center-of-mass energy of 8 TeV. The analysis is based on 13.0 fb−1 of data collected with the ATLAS detector at the LHC. The top squarks are assumed to decay each either to a top quark and the lightest supersymmetric particle (LSP) or each to a bottom quark and a chargino, where the chargino decays to an on- or off-shell W boson and to the LSP. The data are found to be consistent with Standard Model expectations. Assuming both top squarks decay to a top quark and LSP, top squark masses between 225 and 560 GeV are excluded at 95% confidence for massless LSPs, and top squark masses around 500 GeV are excluded for LSP masses up to 175 GeV. Assuming both top squarks decay to a bottom quark and chargino, top squark masses up to 350 GeV are excluded for massless LSPs and a chargino mass of 150 GeV.