Angular dependence of factorial moments in π+/K+p interactions at 250 GeV/c

A sample of π+p and K+p non-diffractive interactions at √s = 22 GeV is used to investigate factorial multiplicity moments as a function of the CMS opening angle θ between particles. The angular dependence is very different for unlike-charge and like-charge particle combinations. For the latter, factorial moments increase with decreasing opening angle approximately as a power law. The θ dependence is stronger for central production-angle intervals than in the forward and backward regions. The predictions of the standard version of the FRITIOF model deviate strongly from the data, but including Bose-Einstein correlations leads to qualitative agreement.