Search for a vector-like bottom quark partner in same sign di-lepton final states

The results of a search for pair-produced vector-like quarks with charge $-\frac{1}{3}$ are presented. The analysis was performed using a dataset of pp collisions at $\sqrt{s}=8$ TeV collected with the CMS detector and corresponding to an integrated luminosity of 19.6 $fb^{-1}$. Events with a same-sign lepton pair and hadronic activity are selected and no excess above expected Standard Model backgrounds is observed. The results are used to set limits on the mass of the ${\rm b}^\prime$ quark as a function of its branching ratio to tW, bZ and bH. The data excludes a ${\rm b}^\prime$ quark with mass less than 800 GeV if the decay is to a top and W exclusively.