Search for production of vector-like quark pairs and of four top quarks in the lepton-plus-jets final state in pp collisions at s=8 TeV with the ATLAS detector

A search for pair production of vector-like quarks, both up-type (T) and down-type (B), as well as for four-top-quark production, is presented. The search is based on pp collisions at s=8$$ \sqrt{s}=8 $$ TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and corresponding