electroweak theory

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electroweak theory,

a unified field theory that describes two of the fundamental forces in nature, electromagnetism (see electromagnetic radiationelectromagnetic radiation,
energy radiated in the form of a wave as a result of the motion of electric charges. A moving charge gives rise to a magnetic field, and if the motion is changing (accelerated), then the magnetic field varies and in turn produces an electric field.
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) and the weak interactionweak interactions,
actions between elementary particles mediated, or carried, by W and Z particles and that are responsible for nuclear decay. Weak interactions are one of four fundamental interactions in nature, the others being gravitation, electromagnetism, and the strong interactions.
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. The electroweak theory derived from efforts to produce a theory for the weak force analogous to quantum electrodynamicsquantum electrodynamics
(QED), quantum field theory that describes the properties of electromagnetic radiation and its interaction with electrically charged matter in the framework of quantum theory.
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 (QED), the quantum theory of the electromagnetic force. Although the weak force fails to meet a requirement for that theory—that it behave the same way at different points in space and time—because it acts only across distances smaller than an atomic nucleus, it was shown that the electromagnetic force, which can extend across interstellar distances, and the weak force are but different manifestations of a more fundamental force, the electroweak force. This made it possible to formulate a unified model that predicted the existence of mediating, or messenger, particles. The electroweak theory, for which Sheldon GlashowGlashow, Sheldon Lee
, 1932–, American physicist, b. New York City, Ph.D. Harvard, 1959. He became a professor at the Univ. of California at Berkeley in 1961 before moving to Harvard in 1967.
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, Abdus SalamSalam, Abdus,
1926–96, Pakistani physicist. After attending Government College at Lahore, he received a Ph.D. from Cambridge (1952). He taught in Lahore for three years before returning to England, first teaching mathematics at Cambridge (1954–57), then moving to
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, and Steven WeinbergWeinberg, Steven,
1933–, American nuclear physicist, b. New York City, Ph.D. Princeton, 1957. Since 1982 he has been a professor at the Univ. of Texas at Austin, having previously been on the faculties of Columbia, the Univ.
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 shared the 1979 Nobel Prize in Physics, was confirmed in 1983 by the discovery of the W and Z particlesW and Z particles,
elementary particles that mediate, or carry, the fundamental force associated with weak interactions. The discovery of the W and Z particles at CERN near Geneva, Switzerland, in the early 1980s was an important confirmation of electroweak theory,
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, two of a number of elementary particleselementary particles,
the most basic physical constituents of the universe. Basic Constituents of Matter

Molecules are built up from the atom, which is the basic unit of any chemical element. The atom in turn is made from the proton, neutron, and electron.
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 it predicted.


See P. Renton, Electroweak Interactions (1990); J. Horejsi, Introduction to Electroweak Unification (1994); A. Salam, Selected Papers of Abdus Salam (1994); J. D. Walecka, Theoretical Nuclear and Subnuclear Physics (1995).

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References in periodicals archive ?
Some scholars proposed the Standard Model of elementary particles, attempting to further unify the QCD and Electroweak theory. This promising unification hypothesis is anticipated to be a huge success, although it does not include the gravitational field.
This similarity suggests a pairing of the electromagnetic and proto-gravity fields in a manner reminiscent of the electroweak theory. [section]7 gives a discussion of the global conservation laws that arise due to symmetries of the flat background.
Veltman, now retired from the University of Michigan in Ann Arbor, invented a calculation technique that made possible ultraprecise predictions of real-world quantities based on the electroweak theory. Their tool, known as dimensional regularization and first described in 1971, also applies to similar theories that describe other forces.
(although physical quark masses are notoriously hard to define [8]) and pretending as if we knew nothing of the electroweak theory (in order not to get entangled with the Higgs mechanism again), using the old Fermi theory for weak interactions (or quantum flavordynamics, QFD) as appropriate for the low energies where observations of physical masses are actually made, using the physical coupling derived from typical scattering cross sections or decay rates ([[tau].sup.-1] [varies] [[alpha].sup.2]), we get, using [[tau].sup.-1.sub.QFD] ~ [10.sup.6][s.sup.-1] (e.g.
of Geneva) covers Lorentz and Poincare symmetries in quantum field theory, classical field theory, quantization of free fields, perturbation theory and Feynman diagrams, cross-section and decay rates, quantum electrodynamics, the low-energy limit of the electroweak theory, path integral quantization, non- abelian gauge theories, and spontaneous symmetry breaking.
Quantum electrodynamics corrects non-relativistic quantum theory, and the Salam-Weinberg electroweak theory corrects quantum electrodynamics.
But that strategy fails when applied to the development of a grand unified theory, which combines the present theory governing quark behavior with the electroweak theory describing the interactions of electrons, photons and related particles.
In the electroweak theory which was constructed several decades later, the W[+ or -] spin-1 charged boson plays a cardinal role.
In the past year, he says, theorists have shown that a complicated phase transition associated with the electroweak theory -- which unites the electromagnetic force with the weak nuclear force responsible for radioactivity -- may produce unequal amounts of matter and antimatter.
This conclusion is relevant to the validity of the electroweak theory and to the meaning of recent results concerning the existence of a particle having a mass of 125 GeV [2,3].
Such precision measurements provide indirect indicators of what physics might (or might not) await us at energy scales not yet reached by present machines, as well as checking further that the electroweak theory really is correct."
According to the standard electroweak theory, that additional effect distorts an atom about as much as a single hair added to Earth's surface changes the planet's shape.