such as between core-contraction of the proto-neutron star (PNS), the accretion neutrino luminosity, and the multi-D hydrodynamic feedback of neutrino-driven convection and the SASI, can be self-consistently determined. On the other hand, the very high computational cost allowed @hanke13 to focus on a single (self-consistent) 3D model, and it has not been clarified yet whether 3D helps or harms the onset of neutrino-driven explosions compared to 2D.

To address this question, we investigate in this paper how the explosion dynamics will differ from 3D to 2D by systematically changing numerical resolutions and initial seed perturbations in multi-D radiation-hydrodynamic simulations. For the multi-group neutrino transport, the isotropic diffusion source approximation (IDSA) scheme [@idsa] is implemented in a ray-by-ray manner (e.g., @takiwaki12 for more details), which we have updated to achieve a very high computational efficiency. As in @takiwaki12, we here focus on the evolution of an $11.2 M_{\odot}$ star of @woos02. We choose this lighter progenitor because the shock revival occurs relatively earlier after bounce (e.g., @buras06) compared to more massive progenitor models as employed in @hanke13. The updated transport scheme together with the employed earlier-to-explode progenitor allow us to conduct a systematic numerical study, for the first time, in both 