Speaker
Description
A search for heavy pseudoscalar ($A$) and scalar ($H$) Higgs
bosons decaying into a top-quark pair ($t\bar{t}$) has been performed in
20.3~fb$^{-1}$ of data collected by the ATLAS experiment at the Large
Hadron Collider in proton--proton collisions at a center-of-mass energy of
$\sqrt{s} = 8$~TeV. No significant deviation from the Standard Model
expectation is observed in the $t\bar{t}$ invariant mass spectrum in final
states with an electron or muon, large missing transverse momentum, and at
least four jets. The results are interpreted in the context of a type-II
Two-Higgs-Doublet Model in the alignment limit. Interference effects
between the signal process and Standard Model $t\bar{t}$ production, which
are expected to distort the signal shape from a single peak to a peak-dip
structure, are taken into account. Exclusion limits on the signal strength
$\mu$ are derived as a function of the mass $m_{A/H}$ and the ratio of the
vacuum expectation values of the two Higgs fields, $\tan\beta$.
| Experimental Collaboration | ATLAS |
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