Higgsless model
Encyclopedia
In particle physics
, a Higgsless model is a model that does not involve the Higgs boson
or in which the Higgs field is not dynamic. Such models must employ a different mechanism of mass
generation, electroweak symmetry breaking
and unitarity
.
In the years since the Higgs mechanism
was first described, there have been several alternatives proposed. All of the alternative mechanisms use strongly interacting dynamics to produce a vacuum expectation value that breaks electroweak symmetry. A partial list of these alternative mechanisms includes:
Particle physics
Particle physics is a branch of physics that studies the existence and interactions of particles that are the constituents of what is usually referred to as matter or radiation. In current understanding, particles are excitations of quantum fields and interact following their dynamics...
, a Higgsless model is a model that does not involve the Higgs boson
Higgs boson
The Higgs boson is a hypothetical massive elementary particle that is predicted to exist by the Standard Model of particle physics. Its existence is postulated as a means of resolving inconsistencies in the Standard Model...
or in which the Higgs field is not dynamic. Such models must employ a different mechanism of mass
Mass
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...
generation, electroweak symmetry breaking
Spontaneous symmetry breaking
Spontaneous symmetry breaking is the process by which a system described in a theoretically symmetrical way ends up in an apparently asymmetric state....
and unitarity
Unitarity (physics)
In quantum physics, unitarity is a restriction on the allowed evolution of quantum systems that insures the sum of probabilities of all possible outcomes of any event is always 1....
.
In the years since the Higgs mechanism
Higgs mechanism
In particle physics, the Higgs mechanism is the process in which gauge bosons in a gauge theory can acquire non-vanishing masses through absorption of Nambu-Goldstone bosons arising in spontaneous symmetry breaking....
was first described, there have been several alternatives proposed. All of the alternative mechanisms use strongly interacting dynamics to produce a vacuum expectation value that breaks electroweak symmetry. A partial list of these alternative mechanisms includes:
- TechnicolorTechnicolor (physics)Technicolor theories are models of physics beyond the standard model that address electroweak symmetry breaking, the mechanism through which elementary particles acquire masses...
models break electroweak symmetry through new gauge interactions, which were originally modeled on quantum chromodynamicsQuantum chromodynamicsIn theoretical physics, quantum chromodynamics is a theory of the strong interaction , a fundamental force describing the interactions of the quarks and gluons making up hadrons . It is the study of the SU Yang–Mills theory of color-charged fermions...
. - Extra-dimensionalExtra dimensionsSeveral speculative physical theories have introduced extra dimensions of space for various reasons:*Kaluza-Klein theory introduces extra dimensions to explain the fundamental forces other than gravity ....
Higgsless models use the fifth component of the gauge fields to play the role of the Higgs fields. It is possible to produce electroweak symmetry breaking by imposing certain boundary conditions on the extra dimensional fields, increasing the unitarityUnitarity (physics)In quantum physics, unitarity is a restriction on the allowed evolution of quantum systems that insures the sum of probabilities of all possible outcomes of any event is always 1....
breakdown scale up to the energy scale of the extra dimension. Through the AdS/QCD correspondence this model can be related to technicolor models and to "UnHiggs" models in which the Higgs field is of unparticleUnparticleIn theoretical physics, Unparticle physics is a speculative theory that conjectures matter that cannot be explained in terms of particles using the Standard Model of particle physics, because its components are scale invariant....
nature. - Models of composite W and Z vector bosons.
- Top quark condensateTop quark condensateIn particle physics, the top quark condensate theory is an alternative to the Standard Model in which a fundamental scalar Higgs field is replaced by a composite field composed of the top quark and its antiquark. These are bound by a four-fermion interaction, analogous to Cooper pairs in a BCS...
. - "Unitary Weyl gauge". If one adds a suitable gravitational term to the standard model action with gravitational coupling, the theory becomes locally scale invariant (i.e. Weyl invariant) in the unitary gauge for the local SU(2). Weyl transformations act multiplicatively on the Higgs field, so one can fix the Weyl gauge by requiring the Higgs scalar to be a constant.
- Asymptotically safe weak interactions based on some nonlinear sigma models.
- "Regular Charge Monopole Theory" by Eliyahu ComayEliyahu ComayEliyahu Comay, is an Israeli theoretical physicist, who published in the fields of classical electrodynamics, quantum mechanics and particle physics...
. - PreonPreonIn particle physics, preons are postulated "point-like" particles, conceived to be subcomponents of quarks and leptons. The word was coined by Jogesh Pati and Abdus Salam in 1974...
and models inspired by preons such as Ribbon model of Standard ModelStandard ModelThe Standard Model of particle physics is a theory concerning the electromagnetic, weak, and strong nuclear interactions, which mediate the dynamics of the known subatomic particles. Developed throughout the mid to late 20th century, the current formulation was finalized in the mid 1970s upon...
particles by Sundance Bilson-ThompsonSundance Bilson-ThompsonSundance Osland Bilson-Thompson is an Australian theoretical particle physicist. He has developed the idea that certain preon models may be represented topologically, rather than by treating preons as pointlike particles. His ideas have attracted interest in the field of loop quantum gravity, as...
, based in braid theoryBraid theoryIn topology, a branch of mathematics, braid theory is an abstract geometric theory studying the everyday braid concept, and some generalizations. The idea is that braids can be organized into groups, in which the group operation is 'do the first braid on a set of strings, and then follow it with a...
and compatible with loop quantum gravityLoop quantum gravityLoop quantum gravity , also known as loop gravity and quantum geometry, is a proposed quantum theory of spacetime which attempts to reconcile the theories of quantum mechanics and general relativity...
and similar theories. This model not only explains mass but leads to an interpretation of electric charge as a topological quantity (twists carried on the individual ribbons) and colour charge as modes of twisting. - Symmetry breaking driven by non-equilibrium dynamics of quantum fields above the electroweak scale .
- Unparticle physics and the unhiggs . These are models that posit that the Higgs sector and higgs boson are scaling invariant, also known as unparticle physics.
- In theory of superfluid vacuumSuperfluid vacuumSuperfluid vacuum theory , sometimes dubbed as the theory of BEC vacuum, is an approach in theoretical physics and quantum mechanics where the physical vacuum is viewed as a superfluid or BEC....
masses of elementary particles can arise as a result of interaction with the physical vacuumVacuumIn everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty". A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in...
, similarly to the gap generation mechanism in superconductors.