A search is presented for new particles in an extension to the Standard Model that includes a heavy Higgs boson ($H^0$), an intermediate charged Higgs-boson pair ($H^{\pm }$), and a light Higgs boson ($h^0$). The analysis searches for events involving the production of a single heavy neutral Higgs boson which decays to the charged Higgs boson and a $W$ boson, where the charged Higgs boson subsequently decays into a $W$ boson and the lightest neutral Higgs boson decaying to a bottom–antibottom-quark pair. Such a cascade results in a $W$-boson pair and a bottom–antibottom-quark pair in the final state. Events with exactly one lepton, missing transverse momentum, and at least four jets are selected from a data sample corresponding to an integrated luminosity of $20.3{\mathrm{fb}}^{-1}$, collected by the ATLAS detector in proton-proton collisions at $\sqrt{s}=8\mathrm{TeV}$ at the LHC. The data are found to be consistent with Standard Model predictions, and 95% confidence-level upper limits are set on the product of cross section and branching ratio. These limits range from 0.065 to 43 pb as a function of $H^0$ and $H^{\pm }$ masses, with $m_{h^0}$ fixed at 125 GeV.

• Received 6 December 2013

DOI:https://doi.org/10.1103/PhysRevD.89.032002

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© 2014 CERN, for the ATLAS Collaboration