Search for scalar top quark pair production in natural gauge mediated supersymmetry models with the ATLAS detector in pp collisions at s=7TeV

The results of a search for pair production of the lighter scalar partners of top quarks (View the MathML source) in 2.05 fb???1 of pp collisions at View the MathML source TeV using the ATLAS experiment at the LHC are reported. Scalar top quarks are searched for in events with two same flavour opposite-sign leptons (e,??) with invariant mass consistent with the Z boson mass, large missing transverse momentum and jets in the final state. At least one of the jets is identified as originating from a b-quark. No excess over Standard Model expectations is found. The results are interpreted in the framework of R-parity conserving, gauge mediated Supersymmetry breaking ???natural??? scenarios, where the neutralino (View the MathML source) is the next-to-lightest supersymmetric particle. Scalar top quark masses up to 310 GeV are excluded for View the MathML source at 95% confidence level, reaching an exclusion of View the MathML source for View the MathML source. Scalar top quark masses below 240 GeV are excluded for all values of View the MathML source.