Multiparticle Dynamics 2004

In high energy collisions of leptons, hadrons and nuclei we observe the production of many particles, mainly hadrons. The ultimate goal in multiparticle production studies is the explanation of the hadronic phenomena within QCD, the basic theory of the strong interactions, along with the other interactions of the standard model and possibly beyond. A basic problem in the QCD study of multiparticle production is the matching of parton and hadron dynamics relevant in the respective weak and strong coupling regimes of QCD. A class of inclusive observables in hard collisions can be computed perturbatively in terms of the running coupling constant αs thanks to the celebrated asymptotic freedom [1]. In practice, it is often required to include some additional non-perturbative input from other sources (e.g. Parton Distribution Functions). Hadronic phenomena can be systematically analysed within lattice gauge theory in sufficiently simple problems. The description of genuine multi-hadron production requires, in addition to the hard QCD part (shower calculus), some phenomenological approaches: specific hadronization models or such simple ideas as “parton hadron duality”. At present, the systematic approach to multi-hadron production based entirely on QCD remains a dream. Is it just a problem of complexity or do we need a fundamentally new insight? In this talk we concentrate on the four topics mentioned in the abstract which represent different variants of the interplay of hard and soft interactions and we emphazise shortly other topics. I am sorry for the incomplete coverage of the many interesting presentations at this conference.