Particle-Set Identification method to study multiplicity fluctuations

In this paper a new method of experimental data analysis, the Particle-Set Identification method, is presented. The method allows to reconstruct moments of multiplicity distribution of identified particles. The difficulty the method copes with is due to incomplete particle identification - a particle mass is frequently determined with a resolution which does not allow for a unique determination of the particle type. Within this method the moments of order $k$ are calculated from mean multiplicities of $k$-particle sets of a given type. %The latter are obtained from a fit to the $k$-dimensional distribution of measured particle masses. The PSET Identification method remains valid even in the case of correlations between mass measurements for different particles. This distinguishes it from the Identity method introduced by us previously to solve the same problem.