  Strongly correlated systems exhibit intriguing properties caused by
intertwined microscopic in- teractions that are hard to disentangle in
equilibrium. Employing non-equilibrium time-resolved photoemission spectroscopy
on the quasi-two-dimensional transition-metal dichalcogenide 1T-TaS$_2$, we
identify a spectroscopic signature of double occupied sites (doublons) that are
reflects fundamental Mott physics. Doublon-hole recombination is estimated to
occur on time scales of one electronic hopping cycle $\hbar/J\approx$ 14 fs.
Despite strong electron-phonon coupling the dynamics can be explained by purely
electronic effects captured by the single band Hubbard model, where
thermalization is fast in the small-gap regime. Qualitative agreement with the
experimental results however requires the assumption of an intrinsic
hole-doping. The sensitivity of the doublon dynamics on the doping level
provides a way to control ultrafast processes in such strongly correlated
materials.
