  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 sqrt(s) = 7 TeV. The measurement is based on 4.7
fb-1 of data collected with the ATLAS detector at the LHC. Each top squark is
assumed to decay to a top quark and the lightest supersymmetric particle (LSP).
The data are found to be consistent with Standard Model expectations. Top
squark masses between 230 GeV and 440 GeV are excluded with 95% confidence for
massless LSPs, and top squark masses around 400 GeV are excluded for LSP masses
up to 125 GeV.
