In nuclear physics and particle physics, the weak interaction

6 min readMay 29, 2021

In nuclear physics and particle physics, the weak interaction, which is also often called the weak force or weak nuclear force, is the mechanism of interaction between subatomic particles that is responsible for the radioactive decay of atoms. The weak interaction participates in nuclear fission, and the theory describing its behaviour and effects is sometimes called quantum flavourdynamics (QFD). However, the term QFD is rarely used, because the weak force is better understood by electroweak theory (EWT).[1]

The effective range of the weak force is limited to subatomic distances, and is less than the diameter of a proton. It is one of the four known force-related fundamental interactions of nature, alongside the strong interaction, electromagnetism, and gravitation.[2]

Background[edit]

The Standard Model of particle physics provides a uniform framework for understanding the electromagnetic, weak, and strong interactions. An interaction occurs when two particles (typically but not necessarily half-integer spin fermions) exchange integer-spin, force-carrying bosons. The fermions involved in such exchanges can be either elementary (e.g. electrons or quarks) or composite (e.g. protons or neutrons), although at the deepest levels, all weak interactions ultimately are between elementary particles.

In the weak interaction, fermions can exchange three types of force carriers, namely W+, W−, and Z bosons. The masses of these bosons are far greater than the mass of a proton or neutron, which is consistent with the short range of the weak force. In fact, the force is termed weak because its field strength over a given distance is typically several orders of magnitude less than that of the strong nuclear force or electromagnetic force.

Quarks, which make up composite particles like neutrons and protons, come in six “flavours” — up, down, strange, charm, top and bottom — which give those composite particles their properties. The weak interaction is unique in that it allows quarks to swap their flavour for another. The swapping of those properties is mediated by the force carrier bosons. For example, during beta minus decay, a down quark within a neutron is changed into an up quark, thus converting the neutron to a proton and resulting in the emission of an electron and an electron antineutrino. Another important example of a phenomenon involving the weak interaction is the fusion of hydrogen into helium that powers the Sun’s thermonuclear process.

Most fermions decay by a weak interaction over time. Such decay makes radiocarbon dating possible, as carbon-14 decays through the weak interaction to nitrogen-14. It can also create radioluminescence, commonly used in tritium illumination, and in the related field of betavoltaics.[3]

The weak interaction is the only fundamental interaction that breaks parity-symmetry, and similarly, the only one to break charge parity symmetry.

During the quark epoch of the early universe, the electroweak force separated into the electromagnetic and weak forces.

History[edit]

In 1933, Enrico Fermi proposed the first theory of the weak interaction, known as Fermi’s interaction. He suggested that beta decay could be explained by a four-fermion interaction, involving a contact force with no range.[4][5]

However, it is better described as a non-contact force field having a finite range, albeit very short.[citation needed] In the 1960s, Sheldon Glashow, Abdus Salam and Steven Weinberg unified the electromagnetic force and the weak interaction by showing them to be two aspects of a single force, now termed the electroweak force.[6][7]

The existence of the W and Z bosons was not directly confirmed until 1983.[8]

https://vexare4629.medium.com/martin-morocky-born-31-march-1983-known-by-his-902c97847c76
https://arrabble.medium.com/mshasho-clothing-is-a-namibian-clothing-brand-founded-db8543163031
https://arrabble.medium.com/martin-morocky-born-31-march-1983-known-by-his-stage-name-as-the-dogg-646979461508
https://vexare4629.medium.com/namibian-music-awards-441b2392403b
https://vexare4629.medium.com/namibia-n%C9%99%CB%88m%C9%AAbi%C9%99-about-this-soundlisten-n%C3%A6%CB%88-16-17-officially-the-republic-of-namibia-e21df090d8c8
https://arrabble.medium.com/an-electromagnetic-field-also-em-field-is-a-classical-i-e-non-quantum-6fc1a608d934

In nuclear physics and particle physics, the weak interaction

Contents

Background[edit]

History[edit]

Written by Jacap