Factorial cumulant moments and correlation integrals in pp collisions at 400 GeV/c

Abstract

The pseudorapidity distribution of charged particles produced in pp collisions at 400 GeV/c was measured by using LEBC films offered by CERN NA27 collaboration. The scaled factorial cumulant moments have been calculated. The results show that the second order cumulants have positive values, while the cumulants of higher order are consistent with zero except for the situation ofnch ≥ 4 events, where the third-order cumulants have positive values beyond the statistical uncertainties. It means that the observed increase of the higherorder factorial momentsFq is almost due to the dynamical two-particle correlation in pp collisions at 400 GeV/c. The cumulant moments also have been calculated by star correlation integrals. It significantly reduced the statistical errors, especially for higher order cumulants. From Monte Carlo events with the same single particle spectrum and no correlations, we observed that for broad mixed-multiplicity distributions, a significant part ofK2 is coming from the single-particle fluctuation due to the fluctuating multiplicity.