Calculating particle correlators with the account of detector efficiency
  The formulae for correlators K2 and K3 of a given particle observable (e.g. energy or transverse momentum) accounting for the track reconstruction efficiency are presented. Similar to the case of an ideal detector, the correlators can be expressed through the event-by-event fluctuation of the observable single event mean and the observable pseudo-central moments. However, on the contrary to the ideal case, this splitting does not allow for a substantial reduction of the computation time. 
Y. A. Kulchitsky, R. Lednicky, F. Rimondi, N. A. Rusakovich, P. V.   Tsiareshka
physics.data-an hep-ex