  Cosmic rays (CRs) interact with turbulent magnetic fields in the intestellar
medium, generating nonthermal emission. After many decades of studies, the
theoretical understanding of their diffusion in the ISM continues to pose a
challenge. This study numerically explores a recent prediction termed "mirror
diffusion" and its synergy with traditional diffusion mechanism based on
gyroresonant scattering. Our study combines 3D MHD simulations of star-forming
regions with test particle simulations to analyze CR diffusion. We demonstrate
the significance of mirror diffusion in CR diffusion parallel to the magnetic
field, when the mirroring condition is satisfied. Our results support the
theoretical expectation that the resulting particle propagation arising from
mirror diffusion in combination with much faster diffusion induced by
gyroresonant scattering resembles a Levy-flight-like propagation. Our study
highlights the necessity to reevaluate the diffusion coefficients traditionally
adopeted in the ISM based on gyroresonant scattering alone. For instance, our
simulations imply a diffusion coefficient $\sim10^{27}cm^2/s$ for particles
with a few hundred TeV within regions spanning a few parsecs around the source.
This estimate is in agreement with gamma-ray observations, which shows the
relevance of our results for understanding of diffuse gamma-ray emission in
star-forming regions.
