Editing Fermi's interaction (section)

{{Short description|Mechanism of beta decay proposed in 1933}}
{{distinguish|Fermi contact interaction}}
{{Use American English|date=January 2019}}
{{Use mdy dates|date=January 2019}}

[[Image:Beta-minus Decay.svg|thumb|360px|{{SubatomicParticle|Beta-}} decay in an [[atomic nucleus]] (the accompanying antineutrino is omitted).
The inset shows beta decay of a free neutron. In both processes, the intermediate emission of a virtual [[W boson|{{SubatomicParticle|W boson-}} boson]] (which then decays to electron and antineutrino) is not shown.]]

In [[particle physics]], '''Fermi's interaction''' (also the '''Fermi theory of beta decay''' or the '''Fermi [[four-fermion interaction]]''') is an explanation of the [[beta decay]], proposed by [[Enrico Fermi]] in 1933.<ref>{{cite journal | last1 = Yang | first1 = C. N. | year = 2012 | title = Fermi's β-decay Theory | journal = Asia Pacific Physics Newsletter | volume = 1 | issue = 1| pages = 27–30 | doi=10.1142/s2251158x12000045}}</ref> The theory posits four [[fermion]]s directly interacting with one another (at one vertex of the associated [[Feynman diagram]]). This interaction explains beta decay of a [[neutron]] by direct coupling of a neutron with an [[electron]], a [[neutrino]] (later determined to be an [[antineutrino]]) and a [[proton]].<ref name="Feynman">{{cite book
|last=Feynman|first=R.P.
|title=Theory of Fundamental Processes
|year=1962
|publisher=[[W. A. Benjamin]]
|at=Chapters 6 & 7
}}</ref>

Fermi first introduced this coupling in his description of beta decay in 1933.<ref name="griffiths">
{{cite book
 |last=Griffiths |first=D.
 |year=2009
 |title=Introduction to Elementary Particles
 |edition=2nd |pages=314–315
 |isbn=978-3-527-40601-2
}}</ref>  The Fermi interaction was the precursor to the theory for the [[weak interaction]] where the interaction between the proton–neutron and electron–antineutrino is mediated by a virtual [[W and Z bosons|W<sup>−</sup> boson]], of which the Fermi theory is the low-energy [[effective field theory]].

According to [[Eugene Wigner]], who together with [[Pascual Jordan|Jordan]] introduced the [[Jordan–Wigner transformation]], Fermi's paper on beta decay was his main contribution to the history of physics.<ref>{{Cite book |title=Fermi Remembered |last=Fermi |first=Enrico |publisher=University of Chicago Press |page=241-244 |date=2004 |isbn=0226121119 }} Edited by [[James Cronin|James W. Cronin]].</ref>