Topcolor is a model in

theoretical physics Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain and predict natural phenomena. This is in contrast to experimental physics, which uses experim ...

, of dynamical

electroweak symmetry breaking In the Standard Model of particle physics, the Higgs mechanism is essential to explain the generation mechanism of the property "mass" for gauge bosons. Without the Higgs mechanism, all bosons (one of the two classes of particles, the other bein ...

in which the

top quark The top quark, sometimes also referred to as the truth quark, (symbol: t) is the most massive of all observed elementary particles. It derives its mass from its coupling to the Higgs Boson. This coupling y_ is very close to unity; in the Standard ...

and anti-top quark form a composite

Higgs boson The Higgs boson, sometimes called the Higgs particle, is an elementary particle in the Standard Model of particle physics produced by the quantum excitation of the Higgs field, one of the fields in particle physics theory. In the Stand ...

by a new force arising from massive "top gluons". The solution to composite Higgs models was actually anticipated in 1981, and found to be the

Infrared fixed point In physics, an infrared fixed point is a set of coupling constants, or other parameters, that evolve from initial values at very high energies (short distance) to fixed stable values, usually predictable, at low energies (large distance). This usu ...

for the

mass.

Analogy with known physics

The composite

made from a bound pair of

top A spinning top, or simply a top, is a toy with a squat body and a sharp point at the bottom, designed to be spun on its vertical axis, balancing on the tip due to the gyroscopic effect. Once set in motion, a top will usually wobble for a few ...

-anti-top quarks is analogous to the phenomenon of

superconductivity Superconductivity is a set of physical properties observed in certain materials where electrical resistance vanishes and magnetic flux fields are expelled from the material. Any material exhibiting these properties is a superconductor. Unlike ...

, where

Cooper pair In condensed matter physics, a Cooper pair or BCS pair (Bardeen–Cooper–Schrieffer pair) is a pair of electrons (or other fermions) bound together at low temperatures in a certain manner first described in 1956 by American physicist Leon Cooper ...

s are formed by the exchange of phonons. The pairing dynamics and its solution was treated in the Bardeen-Hill-Lindner model. The original topcolor naturally involved an extension of the

standard model The Standard Model of particle physics is the theory describing three of the four known fundamental forces (electromagnetism, electromagnetic, weak interaction, weak and strong interactions - excluding gravity) in the universe and classifying a ...

color

gauge group In physics, a gauge theory is a type of field theory in which the Lagrangian (and hence the dynamics of the system itself) does not change (is invariant) under local transformations according to certain smooth families of operations ( Lie group ...

to a product group SU(3)×SU(3)×SU(3)×... One of the gauge groups contains the top and bottom quarks, and has a sufficiently large coupling constant to cause the condensate to form. The topcolor model anticipates the idea of

dimensional deconstruction In theoretical physics, dimensional deconstruction is a method to construct ''4''-dimensional theories that behave as higher-dimensional theories in a certain range of higher energies. The resulting theory is a gauge theory whose gauge group is a di ...

and extra space dimensions, as well as the large mass of the top quark. In 2019 this was revisited ("scalar democracy") in which many composite Higgs bosons may form at very high energies, composed of the known quarks and leptons, perhaps bound by universal force (e.g., gravity, or an extension of topcolor). The standard model

is then a top-anti-top boundstate. The theory predicts many new Higgs doublets, starting at the TeV mass scale, with

\, \mathcal(1) \,

couplings to the known

fermion In particle physics, a fermion is a particle that follows Fermi–Dirac statistics. Generally, it has a half-odd-integer spin: spin , spin , etc. In addition, these particles obey the Pauli exclusion principle. Fermions include all quarks an ...

s, that may explain their masses and mixing angles. The first sequential new Higgs bosons should be accessible to the

LHC The Large Hadron Collider (LHC) is the world's largest and highest-energy particle collider. It was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008 in collaboration with over 10,000 scientists and hundre ...

References

Physics beyond the Standard Model {{particle-stub

Analogy with known physics

See also

References