  We present a new Monte Carlo event generator for the hadronic production of
four top quarks in the POWHEG BOX framework. Besides the dominant
next-to-leading order QCD corrections at $\mathcal{O}(\alpha_s^5)$ we also
include all subleading electroweak productions channels at leading-order
accuracy. We validate our theoretical predictions by comparing to parton-shower
matched predictions obtained within the MC@NLO framework for stable top quarks.
Furthermore, we investigate in detail the various sources of theoretical
uncertainties. Finally, we investigate a single lepton plus jets signature to
study for the first time the impact of the electroweak production modes as well
as spin-correlation effects at the fiducial level.

High Energy Physics - Phenomenology