Conditional Cumulants in Weakly Non-linear Regime

Conditional cumulants form a set of unique statistics which represent a sensible compromise between N -point correlation functions and cumulants measured from moments of counts in cells. They share accurate edge corrected estimators with N -point correlation functions, yet, they are as straightforward to measure and interpret as counts in cells. The conditional cumulants have three equivalent views as i) degenerate N -point correlation functions ii) or integrated monopole moments of the bispectrum iii) they are closely related to neighbour counts. We compute the predictions of weakly non-linear perturbation theory for conditional cumulants and compare them with measurements in simulations, both in real and redshift space. We find excellent agreement between theory and simulations, especially on scales > ∼ 20h Mpc. Due to their advantageous statistical properties and well understood dynamics, we propose conditional cumulants as tools for high precision cosmology. Potential applications include constraining bias and redshift distortions from galaxy redshift surveys.