Abstract
Abstract:
A search is conducted for a beyond-the-Standard-Model boson using events where a Higgs
boson with mass 125 GeV decays to four leptons (t = e or µ). This decay is presumed to occur via an
intermediate state which contains one or two on-shell, promptly decaying bosons: H → Z X/X X → 4t,
where X is a new vector boson Zd or pseudoscalar a with mass between 1 and 60 GeV. The search uses
pp collision data collected with the ATLAS detector at the
LHC with an integrated luminosity of 36.1 fb−1 at a centre-of-mass energy √s = 13 TeV.
No significant excess of events above Standard Model background predictions is observed; therefore,
upper limits at 95% confidence level are set on model-independent fiducial cross- sections, and on
the Higgs boson decay branching ratios to vector and pseudoscalar bosons
in two benchmark models.