A Comparison of Simulated and Analytic Major Merger Counts
  We use large volume, high resolution, N-body simulations of 3 different $\Lambda$CDM models, with different clustering strengths, to generate dark matter halo merging histories. Over the reliable range of halo masses, roughly galaxy groups to rich clusters of galaxies, we quantify the number density of major mergers for two different time intervals and compare with analytic predictions based on the extended Press-Schechter (1974) theory. 
J.D. Cohn, J.S. Bagla, Martin White