Multiparton Distribution Functions In Quantum Chromodynamics

The structure of hadrons (protons) and the dynamics of their interaction are usually studied in collisional experiments by exploring hard single parton-parton scattering described in terms of structure functions (single-particle distributions). Completely new and unique information comes from the selection and analysis of events in which two (or more) hard parton scatterings concurrently occur in a single (p) over barp (Tevatron; FermiLab, USA) or pp (LHC; CERN, Switzerland) collision. The simulation of such double (multiple) parton scatterings involves two-parton (multiparton) distribution functions. Properties of these functions, which may be extracted from quantum chromodynamics, are reviewed.