Intermittency at Intermediate Energies*
Apart from some misunderstandings of this summer, recent developments have led to considerable progress in this controversial but challenging eld. Intermittency is now established as an eeect in at least two dimensions, where it has turned out to be stronger and cleaner than in one. The eeect is strongest in lh and e + e ? collisions. In hh colisions, where the energy range covered is the largest, the eeect is stronger at intermediate then at high p s. Next to parton showering, intermittency is very sensitive to the soft phase, which will have to be studied with large statistics at intermediate energies, where it is not overshadowed by hard eeects. In terms of the space-time development of a scattering process, the intermittency phenomenon and the determination of its parameters are shown to give a genuine information on the nature of hadronization at large distances compared to the hard interaction region. As such, it is expected to be sentitive to the nuclear environment of a deep-inelastic electron collision. In recent years events have been observed containing high particle density \spikes" in rapidity space. Fig.1a shows the JACEE event 1] at a pseudo-rapidity resolution of =0.1 unit, with local uctuations up to dn== 300 and with a signal to background ratio of about 1:1. The NA22 event 2] of Fig.1b contains a rapidity \spike" of dn=dy=100 at a rapidity resolution y=0.1. This corresponds to 60 times the average density in this experiment. Also UA5 3] has reported \spikes" of dn=dd up to 30 (10 times average) as early as JACEE, but found these to be in agreement with a short range cluster Monte Carlo. No doubt, local density uctuations exist. The question is whether they are of statistical or dynamical origin, whether the underlying probability density is continuous or intermittent. To study these, Biaa las and Peschanski 4] have suggested to study the dependence of scaled factorial multiplicity moments
Factorial moments and correlations in meson-nucleus interactions at 250 GeV/c
A sample of 8000 interactions of 250 GeV/c π+ andK+ mesons on Al and Au nuclei, is used to search for intermittency effects by calculating the normalized factorial moments of order two to four. No significant effect is observed in the higher moments. Two-body rapidity correlations and Bose-Einstein correlations in these interactions are presented.
Intermittency and jets
Abstract We show that intermittency, i.e. unlimited growth of multiplicity fluctuations with increasing resolution, is obtained in hadron cascade models with scale invariant branching structure. Strong effects are expected if in a multiparticle event not only the rapidity but simultaneously the azimuthal angle around the beam axis is analysed. The occurrence of narrow jets (“pencil jets”) is expected. The relevance of this type of study for models of hadronization is pointed out.