The Redshift Evolution of LCDM Halo Parameters
  We study the mass and redshift dependence of the concentration parameter in
Nbody simulations spanning masses from $10^{10} \hMsun$ to $10^{15} \hMsun$ and
redshifts from 0 to 2. We present a series of fitting formulas that accurately
describe the time evolution of the concentration-mass relation since z=2. Using
arguments based on the spherical collapse model we study the behaviour of the
scale length of the density profile during the assembly history of haloes,
obtaining physical insights on the origin of the observed time evolution of the
concentration mass relation. We present preliminary results of the
implementation of this model in the prediction of the values of the
concentration parameter for different masses and redshifts.
