cromodinamic

Cromodinamic, also known as quantum chromodynamics (QCD), is the theory that describes the strong interaction between quarks and gluons. It is a non-Abelian gauge theory based on the SU(3) color symmetry. Quarks carry one of three color charges, while gluons carry color-anticolor combinations and act as mediators of the force.

Its defining properties include asymptotic freedom, whereby the strong coupling becomes weaker at high energies, and confinement, which prevents isolated color-charged particles from being observed. The strength of the interaction runs with energy through the running coupling αs(μ).

The theory is formulated by the QCD Lagrangian, containing quark fields, gluon fields, and their interactions through the covariant derivative. At high energies, perturbation theory applies, enabling precise predictions for jet production and scaling violations. At low energies, non-perturbative approaches, especially lattice QCD, are employed to study hadron masses and confinement.

Phenomenology includes the internal structure of hadrons, parton distribution functions, hadron spectroscopy, and jets from collider experiments. Experimental evidence for QCD comes from deep inelastic scattering, measurements of αs, and lattice calculations that reproduce observed hadron spectra.

Historically, asymptotic freedom was established in the 1970s by Gross and Wilczek, with Politzer, leading to QCD as the theory of strong interactions. Its framework underpins much of modern particle physics, from the behavior of jets in high-energy colliders to the masses and interactions of hadrons.