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According to this theory, the character of the strong interaction is determined by a special symmetry between the color charges of the quarks. This symmetry is known as the SU(3) gauge groupGauge theories are a class of physical theories based on the idea that symmetry transformations can be performed locally as well as globally. Most physical theories are described by Lagrangians which are invariant under certain transformations, when the t and the quarks transform under this group as SU(3) triplet Dirac fermionFermions named after Enrico Fermi, are particles which form totally-antisymmetric composite quantum states. As a result, they are subject to the Pauli exclusion principle and obey Fermi-Dirac statistics. The spin-statistics theorem states that fermions haic fieldIn physics, a field is an assignment of a quantity to every point in space. Physicists distinguish between three types of fields, in increasing generality: scalar fields, such as temperature, vector fields, such as the magnitude and direction of the forces. Although the perturbative expansions were important for development of QCD, QCD also predicts many non-perturbative effects such as confinement, fermion condensates and instantons.
Quantum chromodynamics is an important part of the Standard Model of particle physics. The name "chromodynamics" comes from the Greek word "chromos" (color). This name is relevant because the charge of the quarks is usually referred to as " color" although it is unrelated to the visual perception of color.
A particular approach to QCD, namely the lattice models, has enabled the researchers to obtain some theoretical results and quantities that were previously uncalculable.
QCD has a confining phase and a deconfining phase .