Physics:Quantum Electroweak theory: Difference between revisions
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{{Short description|Unified quantum field theory describing the electromagnetic and weak interactions via SU(2) × U(1) gauge symmetry}} | |||
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'''Electroweak theory''' | '''Electroweak theory''' it forms a central part of the Standard Model of particle physics. It forms a central part of the Standard Model of particle physics. Electroweak theory shows that the electromagnetic force and weak nuclear force are different manifestations of a single interaction at high energies. At high energies, they merge into a unified electroweak interaction. The theory is based on the symmetry group: Gauge fields are introduced to preserve local symmetry, leading to four gauge bosons. The electroweak theory predicts four gauge bosons: These combine to form the physical particles: This mixing explains how electromagnetic and weak forces are related. The electroweak symmetry is not directly observed because it is spontaneously broken. | ||
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Latest revision as of 12:26, 20 May 2026
Electroweak theory it forms a central part of the Standard Model of particle physics. It forms a central part of the Standard Model of particle physics. Electroweak theory shows that the electromagnetic force and weak nuclear force are different manifestations of a single interaction at high energies. At high energies, they merge into a unified electroweak interaction. The theory is based on the symmetry group: Gauge fields are introduced to preserve local symmetry, leading to four gauge bosons. The electroweak theory predicts four gauge bosons: These combine to form the physical particles: This mixing explains how electromagnetic and weak forces are related. The electroweak symmetry is not directly observed because it is spontaneously broken.
Unification of forces
Electroweak theory shows that the electromagnetic force and weak nuclear force are different manifestations of a single interaction at high energies.
At low energies:
- electromagnetic interaction → long-range force
- weak interaction → short-range force
At high energies, they merge into a unified electroweak interaction.[1]
Gauge symmetry
The theory is based on the symmetry group:
where:
- acts on left-handed fermions
- corresponds to weak hypercharge
Gauge fields are introduced to preserve local symmetry, leading to four gauge bosons.[2]
Gauge bosons
The electroweak theory predicts four gauge bosons:
- (from )
- (from )
These combine to form the physical particles:
- and (charged weak bosons)
- (neutral weak boson)
- (photon)
This mixing explains how electromagnetic and weak forces are related.[3]
Spontaneous symmetry breaking
The electroweak symmetry is not directly observed because it is spontaneously broken.
This occurs through the Higgs mechanism, introducing a scalar field whose vacuum expectation value selects a specific ground state:
As a result:
- and acquire mass
- the photon remains massless
This explains the short range of the weak interaction.[4]
Electroweak Lagrangian
The electroweak Lagrangian includes:
- fermion kinetic terms
- gauge field terms
- Higgs field contributions
- interaction terms
These components together describe the full dynamics of the electroweak interaction.
Weak interactions
The weak interaction involves processes such as:
- beta decay
- neutrino interactions
- flavor-changing processes
These are mediated by the and bosons.
Experimental confirmation
Electroweak theory has been confirmed by numerous experiments, including:
- discovery of the and bosons
- precision measurements at particle accelerators
- observation of the Higgs boson
These results strongly support the validity of the theory.[2]
Role in the Standard Model
Electroweak theory, together with quantum chromodynamics, forms the core of the Standard Model.
It unifies two of the fundamental forces and provides a consistent framework for describing particle interactions.
Conceptual importance
Electroweak theory demonstrates how gauge symmetry and spontaneous symmetry breaking combine to produce realistic physical theories.
It is a cornerstone of modern particle physics and a key step toward deeper unification.
See also
Table of contents (198 articles)
Index
Full contents
References
- ↑ Peskin, M. E.; Schroeder, D. V. An Introduction to Quantum Field Theory (1995).
- ↑ 2.0 2.1 Schwartz, M. D. Quantum Field Theory and the Standard Model (2014).
- ↑ Cite error: Invalid
<ref>tag; no text was provided for refs namedweinberg - ↑ Higgs, P. W. (1964). Broken symmetries and the masses of gauge bosons.
Source attribution: Physics:Quantum Electroweak theory