Editing Weak interaction (section)

== Background ==

The [[Standard Model]] of [[particle physics]] provides a uniform framework for understanding electromagnetic, weak, and strong interactions. An interaction occurs when two particles (typically, but not necessarily, [[half-integer]] [[Spin (physics)|spin]] [[fermion]]s) exchange integer-spin, force-carrying [[boson]]s. The fermions involved in such exchanges can be either electric  (e.g., [[electron]]s or [[quark]]s) or composite (e.g. [[proton]]s or [[neutron]]s), 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 and Z bosons|{{math|W}}{{sup|+}}, {{math|W}}{{sup|−}}, and {{math|Z}}&nbsp;bosons]]. The [[mass]]es 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.<ref name="hyperphysics">{{cite web |last1=Nave |first1=CR |title=Fundamental Forces - The Weak Force |url=http://hyperphysics.phy-astr.gsu.edu/hbase/Forces/funfor.html |publisher=Georgia State University |access-date=12 July 2023 |archive-url=https://web.archive.org/web/20230402013629/http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html |archive-date=2 April 2023}}</ref> In fact, the force is termed ''weak'' because its [[field strength]] over any set distance is typically several orders of magnitude less than that of the electromagnetic force, which itself is further orders of magnitude less than the strong [[nuclear force]].

The weak interaction is the only fundamental interaction that breaks [[Parity (physics)|parity symmetry]], and similarly, but far more rarely, the only interaction to break [[CP-symmetry|charge–parity symmetry]].

[[Quark]]s, which make up composite particles like neutrons and protons, come in six "flavours"{{snd}} up, down, charm, strange, top and bottom{{snd}} 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. 

Weak interaction is important in the [[Stellar nucleosynthesis#Hydrogen fusion|fusion of hydrogen into helium]] in a star. This is because it can convert a proton (hydrogen) into a neutron to form deuterium which is important for the continuation of nuclear fusion to form helium. The accumulation of neutrons facilitates the buildup of heavy nuclei in a star.<ref name="hyperphysics"/>

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 radioluminescence|tritium luminescence]], and in the related field of [[betavoltaics]]<ref>{{cite press release |title=The Nobel Prize in Physics 1979 |website=NobelPrize.org |publisher=Nobel Media |url=http://nobelprize.org/nobel_prizes/physics/laureates/1979/press.html |access-date=22 March 2011}}</ref> (but ''not'' similar to [[Radium dial|radium luminescence]]).

The [[Electroweak interaction|electroweak force]] is believed to have separated into the electromagnetic and weak forces during the [[quark epoch]] of the [[Chronology of the universe#Early universe|early universe]].