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Encyclopedia > Weak nuclear force
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The weak nuclear force or weak interaction is one of the four fundamental forces of nature. It is most commonly seen in beta decay and the associated radioactivity. The predicate weak derives from the fact that the field strength is some 1013 times less than that of the strong nuclear force. The term nuclear indicates that it is a short-range force, limited to distances smaller than an atomic nucleus. A fundamental interaction is a mechanism by which particles interact with each other, and which cannot be explained by another more fundamental interaction. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... Radioactivity may mean: Look up radioactivity in Wiktionary, the free dictionary. ... The strong nuclear force or strong interaction (also called color force or colour force) is a fundamental force of nature which affects only quarks and antiquarks, and is mediated by gluons in a similar fashion to how the electromagnetic force is mediated by photons. ... A stylized representation of a lithium atom. ...

Contents


Properties

The weak nuclear force affects all leptons and quarks. It is the only force affecting neutrinos (except for gravitation, which is negligible on laboratory scales). The weak interaction enables all lepton and quark particles and antiparticles to interchange energy, mass, electric charge and flavorā€”effectively to change into each other. In physics, a particle is a lepton if it has a spin of 1/2 and does not experience the strong nuclear force. ... For other uses of this term, see: Quark (disambiguation) 1974 discovery photograph of a possible charmed baryon, now identified as the Σc++ In particle physics, the quarks are subatomic particles thought to be elemental and indivisible. ... The neutrino is an elementary particle. ... Jump to: navigation, search Mass is a property of physical objects that, roughly speaking, measures the amount of matter they contain. ... Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interactions. ... In particle physics, flavor is a property of a fermion that identifies it, a label that specifies the name of the particle. ...


Although the weak nuclear force used to be described by Fermi's theory of a contact four-fermion interaction, today we know that it is mediated by the W and Z bosons. Because of their large mass of about 90 GeV/c2, their mean life is limited to about 3 times 10^{-25}seconds by the uncertainty principle: In physics, Fermis interaction is an old explanation of the weak force, proposed by Enrico Fermi. ... Fermions, named after Enrico Fermi, are particles which form totally-antisymmetric composite quantum states. ... In physics, the W and Z bosons are the elementary particles that mediate the weak nuclear force. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... Jump to: navigation, search In quantum physics, the Heisenberg uncertainty principle states that one cannot assign with full precision values for certain pairs of observable variables, including the position and momentum, of a single particle at the same time. ...

Delta EcdotDelta tgeqhbar/2

Even at the speed of light this effectively limits the range of the weak nuclear force to 10 āˆ’ 18 meters, or about 1000 times smaller than the diameter of an atomic nucleus. A stylized representation of a lithium atom. ...


The laws of nature were long thought to remain the same under mirror reflection. The results of an experiment viewed via a mirror were expected to be identical to the results of a mirror-reflected copy of the experimental apparatus. This is called the law of parity conservation in physicists' jargon. However, in the mid-1950's Chen Ning Yang and Tsung-Dao Lee suggested that the weak interaction might violate this law. Chien Shiung Wu and collaborators confirmed this prediction in 1957, earning Yang and Lee the 1957 Nobel Prize in Physics. In 1957, Robert Marshak and George Sudarshan and, somewhat later, Richard Feynman and Murray Gell-Mann proposed a V-A Lagrangian for weak interactions. A physical law or a law of nature is a scientific generalization based on empirical observations. ... Jump to: navigation, search In physics, a parity transformation (also called parity inversion) is the simultaneous flip in the sign of all spatial coordinates: A 3×3 matrix representation of P would have determinant equal to -1, and hence cannot reduce to a rotation. ... In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves. ... Dr. Chen Ning Franklin YANG Chen Ning Franklin YANG (楊振寧 pinyin: Yáng Zhènníng) (born September 22, 1922) is a Chinese American physicist, who worked on statistical mechanics and symmetry principles. ... U.S. government photo Tsung-Dao Lee (李政道 Pinyin: Lǐ Zhèngdào) (born November 24, 1926) is a Chinese American physicist who did work on high energy particle physics, symmetry principles, and statistical mechanics. ... Chien-Shiung Wu (吳健雄 Pinyin: Wú Jiànxíong) (May 31, 1912 - February 16, 1997) was a female Chinese American physicist with an expertise in radioactivity. ... Jump to: navigation, search Hannes Alfvén, 1970 winner for work on astrophysical plasmas List of Nobel Prize laureates in Physics from 1901 to the present day. ... E.C.G. Sudarshan (September 16, 1931, Pallam, in Kottayam district of Kerala) is a prominent Indian physicist and author. ... Jump to: navigation, search Richard Phillips Feynman (May 11, 1918 – February 15, 1988) (surname pronounced FINE-man; in IPA) was one of the most influential American physicists of the 20th century, expanding greatly the theory of quantum electrodynamics. ... Murray Gell-Mann at Harvard University Murray Gell-Mann (born September 15, 1929) is an American physicist who received the 1969 Nobel Prize in physics for his work on the theory of elementary particles. ... A Lagrangian of a dynamical system, named after Joseph Louis Lagrange, is a functional of the dynamical variables which concisely describes the equations of motion of the system. ...


The Standard Model of particle physics describes the electromagnetic force and the weak nuclear force as two different aspects of a single electroweak force, the theory of which was developed around 1968 by Sheldon Glashow, Abdus Salam and Steven Weinberg (more at W and Z bosons). They were awarded the 1979 Nobel Prize in Physics for their work. The Standard Model of Fundamental Particles and Interactions The Standard Model of particle physics is a theory which describes the strong, weak, and electromagnetic fundamental forces, as well as the fundamental particles that make up all matter. ... Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, composed of the electric field and the magnetic field. ... In physics, the electroweak theory presents a unified description of two of the four fundamental forces of nature: electromagnetism and the weak nuclear force. ... Professor Sheldon Lee Glashow (born December 5, 1932) is an American physicist. ... Jump to: navigation, search Prof. ... Steven Weinberg at Harvard University Steven Weinberg (born May 3, 1933) is an American physicist. ... In physics, the W and Z bosons are the elementary particles that mediate the weak nuclear force. ... Jump to: navigation, search Hannes Alfvén, 1970 winner for work on astrophysical plasmas List of Nobel Prize laureates in Physics from 1901 to the present day. ...


Decay via the weak force

A weak decay is the process of decomposing a heavier particle into lighter particles (plus energy) by the weak force.


A typical example is that of beta decay. In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ...


And to put thing on bottoms.


References

  • Griffiths, David J. (1987). Introduction to Elementary Particles, Wiley, John & Sons, Inc. ISBN 0471603864

David J. Griffiths is a U.S. physicist and educator. ...

See also

This article may be too technical for most readers to understand. ...

External links

  • Citation for 1957 Nobel Prize
  • Citation for 1979 Nobel Prize

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