The space-time structure of hadronization in the Lund model

The assumption of linear confinement leads to a proportionality of the energy-momentum and space-time pictures of fragmentation for a simple q (q) over bar system in the Lund string model. The hadronization of more complicated systems is more difficult to describe, and in the past only the energy-momentum picture has been implemented. In this article also the space-time picture isworked out, for open and closed multiparton topologies, for junction systems, and for massive quarks. Some first results are presented, for toy systems but in particular for LHC events. The density of hadron production is quantified under different conditions. The (not unexpected) conclusion is that this density can become quite high, and thereby motivate the observed collective behaviour in high-multiplicity pp collisions. The new framework, made available as part of the Pythia event generator, offers a starting point for future model building in a number of respects, such as hadronic rescattering.