Asymptotic Freedom

In particle physics, asymptotic freedom is a property of some gauge theories that causes interactions between particles to become asymptotically weaker as the energy scale increases and the corresponding length scale decreases.

Particle physics is a branch of physics that studies the nature of the particles that constitute matter and radiation.

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Asymptotic freedom is a feature of quantum chromodynamics, the quantum field theory of the strong interaction between quarks and gluons, the fundamental constituents of nuclear matter.

In nuclear physics and particle physics, the strong interaction is the mechanism responsible for the strong nuclear force, and is one of the four known fundamental interactions, with the others being electromagnetism, the weak interaction, and gravitation.

In theoretical physics, quantum chromodynamics is the theory of the strong interaction between quarks and gluons, the fundamental particles that make up composite hadrons such as the proton, neutron and pion.

In theoretical physics, quantum field theory is a theoretical framework that combines classical field theory, special relativity, and quantum mechanics but not general relativity's description of gravity.

David Gross: Frontiers of Fundamental Physics by Chapman University

Quarks interact weakly at high energies, allowing perturbative calculations.

At low energies the interaction becomes strong, leading to the confinement of quarks and gluons within composite hadrons.

In particle physics, a hadron is a subatomic composite particle made of two or more quarks held together by the strong force in a similar way as molecules are held together by the electromagnetic force.

The asymptotic freedom of QCD was discovered in 1973 by David Gross and Frank Wilczek,

David Jonathan Gross is an American theoretical physicist and string theorist.

and independently by David Politzer in the same year.

Hugh David Politzer is an American theoretical physicist and the Richard Chace Tolman Professor of Theoretical Physics at the California Institute of Technology.

For this work all three shared the 2004 Nobel Prize in Physics.

The Nobel Prize in Physics is a yearly award given by the Royal Swedish Academy of Sciences for those who conferred the most outstanding contributions for mankind in the field of physics.

Asymptotic freedom in QCD was discovered in 1973 by David Gross and Frank Wilczek, and independently by David Politzer in the same year.

The same phenomenon had previously been observed, but its physical significance was not realized until the work of Gross, Wilczek and Politzer, which was recognized by the 2004 Nobel Prize in Physics.

The discovery was instrumental in "rehabilitating" quantum field theory.

Prior to 1973, many theorists suspected that field theory was fundamentally inconsistent because the interactions become infinitely strong at short distances.

This phenomenon is usually called a Landau pole, and it defines the smallest length scale that a theory can describe.

This problem was discovered in field theories of interacting scalars and spinors, including quantum electrodynamics, and Lehman positivity led many to suspect that it is unavoidable.

In geometry and physics, spinors are elements of a complex vector space that can be associated with Euclidean space.

Asymptotically free theories become weak at short distances, there is no Landau pole, and these quantum field theories are believed to be completely consistent down to any length scale.

The Standard Model is not asymptotically free, with the Landau pole a problem when considering the Higgs boson.

The Standard Model of particle physics is the theory describing three of the four known fundamental forces in the universe, as well as classifying all known elementary particles.

Quantum triviality can be used to bound or predict parameters such as the Higgs boson mass. This leads to a predictable Higgs mass in asymptotic safety scenarios.

In other scenarios interactions are weak so that any inconsistency arises at distances shorter than the Planck length.

In physics, the Planck length, denoted ℓP, is a unit of length that is the distance light in a perfect vacuum travels in one unit of Planck time.

The variation in a physical coupling constant under changes of scale can be understood qualitatively as coming from the action of the field on virtual particles carrying the relevant charge.

In physics, a virtual particle is a transient quantum fluctuation that exhibits some of the characteristics of an ordinary particle, while having its existence limited by the uncertainty principle.

In physics, a coupling constant or gauge coupling parameter, is a number that determines the strength of the force exerted in an interaction.

The Landau pole behavior of QED is a consequence of screening by virtual charged particle–antiparticle pairs, such as electron–positron pairs, in the vacuum.

The electron is a subatomic particle, symbol e− or β−, whose electric charge is negative one elementary charge.

The positron or antielectron is the antiparticle or the antimatter counterpart of the electron.

In the vicinity of a charge, the vacuum becomes polarized: virtual particles of opposing charge are attracted to the charge, and virtual particles of like charge are repelled.