Search B' to bZ

A search is presented for the pair production of a charge $-1/3$ vector-like quark, B$'$, that has a 100\% branching fraction into a bottom quark and a Z~boson. Data corresponding to integrated luminosity of 4.9~fb$^{-1}$ from pp~collisions at $\sqrt{s} = 7$~TeV collected with the CMS detector at the LHC were used. The invariant mass spectrum of b-tagged jets and Z~boson candidates, with the latter identified through e$^{+}$e$^{-}$ or $\mu^{+}\mu^{-}$ decays, is examined for an excess of events and found to be consistent with the standard model expectations. The expected 95\% confidence level lower limit on the mass of the B$'$~quark is 510~GeV$/c^{2}$, while the observed lower limit is 550~GeV$/c^{2}$.