  Multiorbital interactions have the capacity to produce an interesting kind of
doublon-holon bound state that consists of a single-hole state in one band and
a doubly-occupied state in another band. Interband doublon-holon pair
excitations in the two-orbital Hubbard model are studied by using dynamical
mean-field theory with the Lanczos method as the impurity solver. We find that
the interband bound states may provide several in-gap quasiparticle peaks in
the density of states of the narrow band in the orbital-selective Mott phase
with a small Hund's rule coupling ($J$). There exists a corresponding energy
relation between the in-gap states of the narrow band and the peaks in the
excitation spectrum of the doublon for the wide band. We also find that the
spin flip and pair-hopping Hund interactions can divide one quasiparticle peak
into two peaks, where the splitting energy increases linearly with increasing
$J$. Strong Hund's rule coupling can move the interband doublon-holon pair
excitations outside the Mott gap and restrict the bound states by suppressing
the orbital selectivity of the doubly-occupied and single-hole states.
