  We use broadband ultra-fast pump-probe spectroscopy in the visible range to
study the lowest excitations across the Mott-Hubbard gap in the orbitally
ordered insulator YVO3. Separating thermal and non-thermal contributions to the
optical transients, we show that the total spectral weight of the two lowest
peaks is conserved, demonstrating that both excitations correspond to the same
multiplet. The pump-induced transfer of spectral weight between the two peaks
reveals that the low-energy one is a Hubbard exciton, i.e. a resonance or bound
state between a doublon and a holon. Finally, we speculate that the pump-driven
spin-disorder can be used to quantify the kinetic energy gain of the excitons
in the ferromagnetic phase.
