Search for a multi-Higgs-boson cascade in WWbb events with the ATLAS detector in pp collisions at √s=8 TeV

A search is presented for new particles in an extension to the Standard Model that includes a heavy Higgs
boson (H0), an intermediate charged Higgs-boson pair (H), and a light Higgs boson (h0). 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 fb−1, collected by the ATLAS detector in proton-proton collisions at
pffisffiffi ¼ 8 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 H0 and H masses, with mh0 fixed at 125 GeV.