Search for a heavy partner of the top quark with charge 5/3

A search for the production of heavy partners of the top quark with charge 5/3 in same sign leptonic events is presented. The data sample corresponds to an integrated luminosity of ${\cal{L}}=5$\,fb$^{-1}$ and was collected at a center of mass energy of $\sqrt{s}=7$~TeV by the CMS experiment at the Large Hadron Collider. No significant excess is observed in the data above the expected standard model background. Upper bounds at the 95\% confidence level are set on the production cross section of heavy top quark partners and masses below 645~GeV are excluded.