PERTURBATIVE UNIVERSALITY IN SOFT PARTICLE-PRODUCTION-B

The spectrum of partons in a QCD jet becomes independent of the primar y energy in the low momentum limit. This follows within the perturbati ve QCD from the colour coherence in soft gluon branching. Remarkably, the hadrons follow such behaviour closely, suggesting the parton hadro n duality picture to be appropriate also for the low momentum particle s. More generally, this scaling property holds for particles of low tr ansverse and arbitrary longitudinal momentum, which explains an old ex perimental observation (:''fan invariance:''). Further tests of the pe rturbatively based picture for soft particle production are proposed f or three-jet events in e(+)e(-) annihilation and di-jet production eve nts in gamma p, gamma gamma and p (p) over bar collisions. They are ba sed upon the difference in the intensity of the soft radiation from pr imary q (q) over bar and gg antennae.