We discuss an event-by-event treatment of the hydrodynamical evolution in heavy ion collisions and also high multiplicity pp scatterings at the LHC. The initial conditions are flux-tubes, as a consequence of elementary multiple scatterings, treated in the framework of Gribov-Regge theory (compatible with pQCD on the level of inclusive cross sections). We will discuss qualitative features of our approach and our understanding of first LHC results (QGP formation in pp? Interpretation of “ridges” in pp and PbPb), but we will also provide some discussion about the theoretical basis of the multiple scattering aspect.

SUBATECH, U. Nantes