Relativistic heavy-ion collisions provide a unique environment to study matter under extreme conditions of high temperature andenergy density. In the soft pT region (< 2 GeV/c) particle production is governed by the bulk properties (e.g. hydrodynamic pressure, freeze-out temperature) of the collisions.Total particle yields as well as their distributions in phase space are strongly dependent on these properties. These bulk properties will be discussed and we will compare our heavy-ion results to measurements in the p+p reference system, where multiparticle processes such as recombination and rescattering are generally thought to be negligible. However, we will show evidence for pi+ pi- rescattering interactions even in p+p collisions.
Soft interaction; Elliptic flow; Mass modification
