Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons ( ${\mathrm{H}}$ ) in proton-proton collisions collected by the CMS experiment at the LHC at $\sqrt{s}=8\,\text {TeV}$ . The data correspond to an integrated luminosity of 19.7 $\,\text {fb}^{-1}$ . The search considers ${\mathrm{H}} {\mathrm{H}}$ resonances with masses between 1 and 3 $\,\text {TeV}$ , having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and ${\mathrm{t}}\overline{{\mathrm{t}}}$ events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 % confidence level for the product of the production cross section and branching fraction $\sigma ({{\mathrm{g}} {\mathrm{g}}} \rightarrow \mathrm {X})\, \mathcal {B}({\mathrm {X}} \rightarrow {\mathrm{H}} {\mathrm{H}} \rightarrow {\mathrm{b}} \overline{{\mathrm{b}}} {\mathrm{b}} \overline{{\mathrm{b}}} )$ range from 10 to 1.5 $\text {\,fb}$ for the mass of X from 1.15 to 2.0 $\,\text {TeV}$ , significantly extending previous searches. For a warped extra dimension theory with a mass scale $\Lambda _\mathrm {R} = 1$ $\,\text {TeV}$ , the data exclude radion scalar masses between 1.15 and 1.55 $\,\text {TeV}$ .