Search for pair-produced vector-like quarks of charge -1/3 decaying to bH using boosted Higgs jet-tagging in pp collisions at sqrt(s) = 8 TeV

A search is performed for the pair-production of a heavy vector-like quark ${\rm b'}$ of charge $-1/3$ and its anti-particle, using data collected by the CMS experiment, from the LHC pp collisions at centre-of-mass energy of 8 TeV and corresponding to an integrated luminosity of 19.7 fb$^{-1}$. We search for the ${\rm b'}$ quark decaying to a Higgs-boson and a b quark, assuming a branching ratio of 100$\%$, in a final state containing a fat jet to reconstruct the boosted Higgs boson and one or more b-tagged jets. The multijets background is evaluated entirely from the data while the t$\overline{\rm t}$+jets background is obtained from simulations. In the absence of a signal excess significantly above the estimated background, we place a limit on the ${\rm b'}$ quark-antiquark pair-production cross section and hence on the ${\rm b'}$ quark mass. We exclude ${\rm b'}$ quarks for masses below 846 GeV at 95$\%$ confidence level, while the expected limit is 811 GeV.