(Medium-modified) fragmentation functions

We discuss some of the recent advances in the field of parton fragmentation processes into hadrons as well as their possible modifications in QCD media. Hadron-production data in e ⁺ e ⁻, deep inelastic scattering and hadronic collisions are presented, together with global analyses of fragmentation functions into light and heavy hadrons and developments on parton fragmentation in perturbative QCD at small momentum fraction. Motivated by the recent RHIC data indicating a significant suppression of large-p _⊥ hadron production in heavy-ion collisions, several recent attempts to model medium-modified fragmentation, e.g. by solving “medium” evolution equations or through Monte Carlo studies, have been proposed and are discussed in detail. Finally, we mention the possibility to extract medium-modified fragmentation functions using photon–hadron correlations.