Search for exotic same-sign dilepton signatures ($b'$ quark, $T_{5/3}$ and 4 top quarks production) in 4.7 fb$^{-1}$ of pp collisions at $sqrt{s}$ = 7 TeV with the ATLAS detector

This proceeding present a search for exotic processes - pair production of down-type heavy quarks ($b'$), single and pair production of heavy top quark partners ($T_{5/3}$), and production of events containing four top quarks ($ttar{tt}$) - in pp collisions at $sqrt{s}$ = 7 TeV recorded with the ATLAS detector. For an integrated luminosity of 4.7 fb$^{-1}$, the corresponding lower limit on both the $b'$ and $T_{5/3}$ mass is 0.67 TeV at 95% confidence level, when produced in pairs. When including the single production mechanism, limits on $T_{5/3}$ production are 0.68 TeV and 0.70 TeV for a coupling constant of the ($tWT_{5/3}$) vertex equal to 1 and 3, respectively. The upper limit on the four top quarks production cross section is 61 fb at 95% confidence level.