Search for direct production of the top squark in the all-hadronic ttbar + etmiss final state in 21 fb-1 of p-pcollisions at sqrt(s)=8 TeV with the ATLAS detector

The results of a search for direct pair production of scalar partners of the top quark in 20.5 fb-1 of pp collisions at sqrt(s)=8 TeV using the ATLAS detector at the LHC are reported. The top squarks are assumed to decay exclusively into a top quark and the lightest supersymmetric particle. The search is conducted in events with large missing transverse momentum and six or more jets, targeting the fully-hadronic top final state. Results are interpreted in a R-parity conserving minimal supersymmetric scenario of direct top squark pair production. Top squarks in this model with masses between 320 and 660 GeV are excluded at 95% CL for a nearly massless LSP. For a LSP mass of 150 GeV the exclusion interval is between 400 and 620 GeV. The result significantly extends previous limits in the all-hadronic final state and excludes top squarks up to higher masses than in previous searches.