Asymptotic freedom

Asymptotic freedom is the property of quantum chromodynamics in which the strong interaction becomes weaker at shorter distances, or equivalently at higher energies.

Quantum chromodynamics: The quantum field theory describing quarks, gluons, and the strong interaction. Asymptotic freedom is a defining short-distance property of this theory.
David Gross: An American theoretical physicist who made foundational contributions to quantum chromodynamics and string theory. He co-discovered asymptotic freedom in 1973.
Deep inelastic scattering: A scattering process in which high-energy leptons probe the internal structure of nucleons. Its measurements revealed quark-like constituents and tested short-distance QCD.
Quark confinement: The phenomenon that quarks and gluons are not observed as isolated particles at long distances. It contrasts the weak short-distance interaction with QCD’s strong long-distance behavior.
Renormalization group: A framework for tracking how a theory’s parameters change with the scale of observation. It describes how the strong coupling changes with energy.
Frank Wilczek: An American theoretical physicist whose work includes quantum chromodynamics and asymptotic freedom. He co-discovered the weakening of the strong coupling at high energies.
Jets (particle physics): Collimated sprays of hadrons produced when energetic quarks or gluons fragment. Their production rates and structure test perturbative QCD at high energies.
Quantum electrodynamics: The quantum field theory of electromagnetic interactions between electrically charged particles. Its effective coupling grows, rather than weakens, at higher energies.
Beta function: A function describing how a coupling constant varies with energy scale. Its negative sign at high energies produces asymptotic freedom in QCD.
H. David Politzer: An American theoretical physicist whose work established asymptotic freedom in quantum chromodynamics. His independent 1973 discovery completed the foundational result.

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