A redshift distortion free correlation function at third order in the
  nonlinear regime
  The zeroth-order component of the cosine expansion of the projected
three-point correlation function is proposed for clustering analysis of cosmic
large scale structure. These functions are third order statistics but can be
measured similarly to the projected two-point correlations. Numerical
experiments with N-body simulations indicate that the advocated statistics are
redshift distortion free within 10% in the non-linear regime on scales
~0.2-10Mpc/h. Halo model prediction of the zeroth-order component of the
projected three-point correlation function agrees with simulations within ~10%.
This lays the ground work for using these functions to perform joint analyses
with the projected two-point correlation functions, exploring galaxy clustering
properties in the framework of the halo model and relevant extensions.
