electroweak theory

electroweak theory
/i lek"troh week'/, Physics.
a gauge theory that unifies quantum electrodynamics with the theory of weak interactions. Also called Salam-Weinberg theory, Weinberg-Salam theory. Cf. intermediate vector boson.
[1975-80; ELECTRO- + WEAK; alternate name after U.S. physicist Steven Weinberg (born 1933) and Pakistani physicist Abdus Salam (born 1926)]

* * *

Theory that describes both the electromagnetic force and the weak force. Though the forces appear to be different, they are actually different facets of a more fundamental force. This theory, formulated in the 1960s by Sheldon Glashow

born 1932

, Steven Weinberg

born 1933

, and Abdus Salam

born 1926

, represents a 20th-century scientific landmark and won its authors a 1979 Nobel Prize.

It was validated in the 1980s with the discovery of the W particle and Z particle, which it had predicted. See also fundamental interaction, unified field theory.

* * *

      in physics, the theory that describes both the electromagnetic force (electromagnetism) and the weak force. Superficially, these forces appear quite different. The weak force acts only across distances smaller than the atomic nucleus, while the electromagnetic force can extend for great distances (as observed in the light of stars reaching across entire galaxies), weakening only with the square of the distance. Moreover, comparison of the strength of these two fundamental interactions (fundamental interaction) between two protons (proton), for instance, reveals that the weak force is some 10 million times weaker than the electromagnetic force. Yet one of the major discoveries of the 20th century has been that these two forces are different facets of a single, more-fundamental electroweak force.

      The electroweak theory arose principally out of attempts to produce a self-consistent gauge theory for the weak force, in analogy with quantum electrodynamics (QED), the successful modern theory of the electromagnetic force developed during the 1940s. There are two basic requirements for the gauge theory of the weak force. First, it should exhibit an underlying mathematical symmetry, called gauge invariance, such that the effects of the force are the same at different points in space and time. Second, the theory should be renormalizable (renormalization); i.e., it should not contain nonphysical infinite quantities.

      During the 1960s Sheldon Lee Glashow (Glashow, Sheldon Lee), Abdus Salam (Salam, Abdus), and Steven Weinberg (Weinberg, Steven) independently discovered that they could construct a gauge-invariant theory of the weak force, provided that they also included the electromagnetic force. Their theory required the existence of four massless “messenger” or carrier particles, two electrically charged and two neutral, to mediate the unified electroweak interaction. The short range of the weak force indicates, however, that it is carried by massive particles. This implies that the underlying symmetry of the theory is hidden, or “broken,” by some mechanism that gives mass to the particles exchanged in weak interactions but not to the photons exchanged in electromagnetic interactions. The assumed mechanism involves an additional interaction with an otherwise unseen field, called the Higgs field (Higgs particle), that pervades all space.

      In the early 1970s Gerardus 't Hooft (Hooft, Gerardus 't) and Martinus Veltman (Veltman, Martinus J.G.) provided the mathematical foundation to renormalize the unified electroweak theory proposed earlier by Glashow, Salam, and Weinberg. Renormalization removed the physical inconsistencies inherent in earlier calculations of the properties of the carrier particles, permitted precise calculations of their masses, and led to more-general acceptance of the electroweak theory. The existence of the force carriers, the neutral Z particles (Z particle) and the charged W particles (W particle), was verified experimentally in 1983 in high-energy proton-antiproton collisions at the European Organization for Nuclear Research ( CERN). The masses of the particles were consistent with their predicted values.

      The characteristics of the unified electroweak force, including the strength of the interactions and the properties of the carrier particles, are summarized in the standard model of particle physics (physics).

Christine Sutton
 

* * *


Universalium. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • electroweak theory — /i lek troh week /, Physics. a gauge theory that unifies quantum electrodynamics with the theory of weak interactions. Also called Salam Weinberg theory, Weinberg Salam theory. Cf. intermediate vector boson. [1975 80; ELECTRO + WEAK; alternate… …   Useful english dictionary

  • electroweak theory — /əˌlɛktroʊˈwik θɪəri/ (say uh.lektroh week thearree) noun a theory which combines the electromagnetic interaction and the weak interaction in one set of equations …  

  • Electroweak epoch — In physical cosmology the electroweak epoch was the period in the evolution of the early universe when the temperature of the universe was high enough to merge electromagnetism and the weak interaction into a single electroweak interaction (> 100 …   Wikipedia

  • theory — /thee euh ree, thear ee/, n., pl. theories. 1. a coherent group of general propositions used as principles of explanation for a class of phenomena: Einstein s theory of relativity. 2. a proposed explanation whose status is still conjectural, in… …   Universalium

  • Electroweak scale — In particle physics, the electroweak scale is the energy scale around 246 GeV, a typical energy of processes described by the electroweak theory. The particular number 246 GeV is taken to be the vacuum expectation value v = (G F sqrt{2})^{ 1/2}… …   Wikipedia

  • electroweak — ə̇¦lektrōˌ, ē¦l adjective Etymology: electr + weak : of, relating to, or being the unification of electromagnetism and the weak force electroweak theory …   Useful english dictionary

  • electroweak — [ē lek′trō wēk΄, ilek′trō wēk΄] adj. designating or of the theory that combines the electromagnetic interaction with the weak interaction and predicts the behavior of the W and Z particles * * * e·lec·tro·weak (ĭ lĕk trō wēkʹ) adj. Of or relating …   Universalium

  • electroweak — [ē lek′trō wēk΄, ilek′trō wēk΄] adj. designating or of the theory that combines the electromagnetic interaction with the weak interaction and predicts the behavior of the W and Z particles …   English World dictionary

  • Electroweak interaction — In particle physics, the electroweak interaction is the unified description of two of the four fundamental interactions of nature: electromagnetism and the weak interaction. Although these two forces appear very different at everyday low energies …   Wikipedia

  • Theory of everything — A theory of everything (TOE) is a putative theory of theoretical physics that fully explains and links together all known physical phenomena. Initially, the term was used with an ironic connotation to refer to various overgeneralized theories.… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”