An Excessive Core Collapse in Nbody Cosmological simulations
  The particle mass used in cosmology N-body simulations is close to
$10^{8}M_{\odot}$, which is about $10^{65}$ times larger than the GeV scale
expected in particle physics. However, self-gravity interacting particle
systems made up of different particles mass have different statistical and
dynamical properties. Here we demonstrate that, due to this particle mass
difference, the nowaday cosmology N-body simulations can have introduced an
excessive core collapse process, especially for the low mass halos at high
redshift. Such dynamical effect introduces an excessive cuspy center for these
small halos, and it implies a possible connection to the so called "small scale
crisis" for CDM models. Our results show that there exist a physical limit in
cosmological simulations, by using about $10^3$ particles to describe smallest
halos, and we provide a simple suggestion based on it to relieve those effects
from the bias.
