  We assess the accuracy of the ghost-rotationally-invariant slave-boson
(g-RISB) theory in multiorbital systems by applying it to both the
three-orbital degenerate Hubbard model and a realistic Sr2RuO4 model extracted
from first principle simulations, and comparing the results to those obtained
using the dynamical mean-field theory (DMFT). Our findings indicate that
g-RISB's accuracy can be systematically improved toward the exact DMFT limit in
infinite dimensional multiorbital models by increasing the number of ghost
orbitals. This allows for a more precise description of aspects of Hund metal
physics and Mott physics compared to the original RISB approach. We also
demonstrate that g-RISB reliably captures the quasiparticle weights, Fermi
surface, and low-energy spectral function for the realistic Sr2RuO4 model
compared to DMFT. Moreover, we showcase the potential of using the density
matrix renormalization group method as an impurity solver within the g-RISB
framework to study systems with a larger number of ghost orbitals. These
results show the potential of g-RISB as a reliable tool for simulating
correlated materials. The connection between the g-RISB and DMFT self-energy is
also discussed.
