Search for Vector-Like b' Pair Production with Multilepton Final States in pp collisions at sqrt(s) = 8 TeV

A search for pair-production of vector-like partners of the b quark, b$^\prime$, is carried out in events with at least three leptons using 19.5 fb$^{-1}$ of integrated luminosity in $\textrm{pp}$ collisions at $\sqrt{s}=8$ TeV collected by the CMS experiment at the LHC. The data are binned in multiple exclusive channels according to the amount of expected standard model background in order to increase the search sensitivity. The observations are consistent with the standard model expectations. The search is interpreted for different b$^\prime$ masses and for varying branching ratios to the $\textrm{bZ}$, $\textrm{tW}$, and $\textrm{bH}$ states. We exclude b$^\prime$ quarks with masses less than values in the range of 520$-$785 GeV (depending on the values of the branching ratios) at the 95$\%$ confidence level.