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{{distinguish|Fermi contact interaction}}
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[[Image:Beta-minus Decay.svg|thumb|360px|{{SubatomicParticle|Beta-}} decay in an [[atomic nucleus]] (the accompanying antineutrino is omitted).<br>
The inset shows beta decay of a free neutron.<br>
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''') is an explanation of the [[beta decay]], proposed by [[Enrico Fermi]] in 1933.<ref>"Tentativo di una teoria dei raggi β", Ricerca Scientifica, 1933 (also Z. Phys., 1934)</ref><ref>
{{Cite web
| last = Fermi | first = E.
| title = Fermi's Theory of Beta Decay (English translation by Fred L. Wilson, 1968)
| work = [[American Journal of Physics]]
| year = 1934
| url = http://microboone-docdb.fnal.gov/cgi-bin/RetrieveFile?docid=953;filename=FermiBetaDecay1934.pdf;version=1
}}</ref> The theory posits four [[fermion]]s directly interacting with one another, at one vertex.<br>
For example, this interaction explains beta decay of a [[neutron]] by direct coupling of a neutron  with:
# an [[electron]],
# 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 }} 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=David|title=Introduction to Elementary Particles |year=2009|isbn=978-3-527-40601-2|pages=314–315}}</ref>
# virtual [[W and Z bosons|W<sup>-</sup> boson]]
 
== History of initial rejection and later publication ==
Fermi first submitted his "tentative" theory of beta decay to the famous science journal ''[[Nature (journal)|Nature]]'', which rejected it for being "too speculative." ''Nature'' later admitted the rejection to be one of the great editorial blunders in its history. Fermi then submitted the paper to [[italian language|Italian]] and [[german language|German]] publications, which accepted and published it in 1933 in those languages, but it did not appear at the time in a primary publication in English (''[[Nature (journal)|Nature]]'' finally belatedly republished Fermi's report on beta decay in English on January&nbsp;16, 1939).
 
Fermi found the initial rejection of the paper so troubling that he decided to take some time off from [[theoretical physics]], and do only experimental physics. This would lead shortly to his famous work with [[neutron temperature|activation of nuclei]] with slow neutrons.
 
==The nature of the interaction==
 
The interaction could also explain [[muon]] decay via a coupling of a muon, electron-antineutrino, muon-neutrino and electron, with the same fundamental strength of the interaction. This hypothesis was put forward by [[Gershtein]] and [[Zeldovich]] and is known as the [[Conserved Vector Current]] hypothesis.<ref name="gerstein1958">Gerstein, S S; Zeldovich Ya B. (1958) Soviet Physics. JFTP. 8, 570</ref>
 
Fermi's four-fermion theory describes the [[weak interaction]] remarkably well. Unfortunately, the calculated cross-section grows as the square of the energy <math> \sigma \approx G_{\rm F}^2 E^2 </math>, making it unlikely that the theory is valid at energies much higher than about 100 GeV. The solution is to replace the four-fermion contact interaction by a more complete theory ([[UV completion]])—an exchange of a [[W and Z bosons|W or Z boson]] as explained in the [[electroweak theory]].
 
In the original theory, Fermi assumed that the form of interaction is a contact coupling of two vector currents. Subsequently, it was pointed out by [[Tsung-Dao Lee|Lee]] and [[Chen Ning Yang|Yang]] that nothing prevented the appearance of an axial, parity violating current, and this was confirmed by [[Wu Experiment|experiments]] carried out by [[Chien-Shiung Wu]].<ref>
{{cite journal
|last1=Lee |first1=T. D.
|last2=Yang |first2=C. N.
|year=1956
|title=Question of Parity Conservation in Weak Interactions
|journal=[[Physical Review]]
|volume=104 |issue=1 |pages=254–258
|bibcode = 1956PhRv..104..254L
|doi=10.1103/PhysRev.104.254
}}</ref><ref>
{{cite journal
|last1=Wu |first1=C. S.
|last2=Ambler |first2=E
|last3=Hayward |first3=R. W.
|last4=Hoppes |first4=D. D.
|last5=Hudson |first5=R. P.
|year=1957
|title=Experimental Test of Parity Conservation in Beta Decay
|journal=[[Physical Review]]
|volume=105 |issue=4 |pages=1413–1415
|bibcode=1957PhRv..105.1413W
  |doi=10.1103/PhysRev.105.1413
}}</ref>
 
{| class="wikitable" style="float:right; clear:right; margin-top:0; margin-left:10px; margin-bottom:8px; margin-right:0; padding:7px; font-size:85%; width:230px;"
|-
| {{nowrap|[[File:MuonFermiDecay.gif|x110px]]&nbsp;}}
|-
| Fermi's interaction showing the 4-point fermion vector current, coupled under Fermi's Coupling Constant {{math|''G''<sub>F</sub>}}. Fermi's Theory was the first theoretical effort in describing nuclear  decay rates for Beta-Decay.  
|}
 
The inclusion of Parity violation in Fermi's interaction was done by [[George Gamow]] and [[Edward Teller]] in the so-called Gamow-Teller Transitions which described Fermi's interaction in terms of Parity violating "allowed" decays and Parity conserving "superallowed" decays in terms of anti-parallel and parallel electron and neutrino spin states respectively. Before the advent of the electroweak theory and the [[Standard Model]], [[George Sudarshan]] and [[Robert Marshak]], and also independently [[Richard Feynman]] and [[Murray Gell-Mann]], were able to determine the correct [[tensor]] structure ([[vector (geometric)|vector]] minus [[axial vector]], {{math|''V'' − ''A''}}) of the four-fermion interaction.
 
==Fermi constant==
The strength of Fermi's interaction is given by the Fermi coupling constant {{math|''G''<sub>F</sub>}}. The most precise experimental determination of the Fermi constant comes from measurements of the muon [[Exponential decay|lifetime]], which is inversely proportional to the square of {{math|''G''<sub>F</sub>}} (when neglecting the muon mass against the mass of the W boson).<ref name="mulan">D. Chitwood et al., Phys.Rev.Lett. 99 (2007) 032001</ref> In modern terms:<ref name=griffiths />
 
<math>
\frac{G_{\rm F}}{(\hbar c)^3}=\frac{\sqrt{2}}{8}\frac{g^{2}}{m_{\rm W}^{2}}=1.16637(1)\times10^{-5} \; \textrm{GeV}^{-2} \ .</math>
 
Here {{mvar|g}} is the [[coupling constant]] of the [[weak interaction]], and {{math|''m''<sub>W</sub>}} is the mass of the [[W boson]] which mediates the decay in question.
 
In the Standard Model, Fermi's constant is related to the [[Higgs mechanism|Higgs vacuum expectation value]] <math>v = (\sqrt{2}G_{\rm F})^{-1/2} \simeq 246.22 \; \textrm{GeV}</math><ref>{{cite journal|last=Plehn|first=Tilman|coauthors=Rauch, Michael|journal=Phys. Rev. D|year=2005|volume=72|pages=053008|doi=10.1103/PhysRevD.72.053008|arxiv = hep-ph/0507321 |bibcode = 2005PhRvD..72e3008P }}</ref>
 
==References==
{{Reflist|2}}
 
{{Four-fermion interactions}}
 
{{DEFAULTSORT:Fermi's Interaction}}
[[Category:Particle physics]]
[[Category:Quantum field theory]]
[[Category:Enrico Fermi|Interaction]]

Latest revision as of 17:18, 25 May 2014

This can a strategy and as well as battle activation where you must manage your hold tribe and also prevent leakages. You have so that it will build constructions which may possibly provide protection for your individual soldiers along with a person's instruction. First completely focus on your protection and after its recently long been taken treatment. You will need to move forward offering the criminal offense arrange. As well as your Military facilities, you also need to keep in thought processes the way your tribe is certainly going. For instance, collecting time and energy as well as fostering your own tribe could be the key to good findings.

Video gaming are fun to use your kids. Aids you learn much more details about your kid's interests. Sharing interests with your kids like this can will also create great conversations. It also gives an opportunity to monitor increase of their skills.

Vehicle which play clash of clans are searching for ways of getting spare gems. The treasures are very important they give the player capabilities and the power to boost their gaming experience. As opposed to several other equivalent games in mobile websites, especially those where individuals use various splits in buy to bring these practical information referring to free, the nature from farmville and its layout does not enable nearly any varieties of hacks that an individual can put to the game. Everyone is always looking for ways for you to get free gems into clash of clans even so most important thing carry out is to employ a great venue to earn these people for free, save each of them suitably and use available where necessary.

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Ideal some online games provde the comfort of adding a true-entire world clock accessible in the movie clip game itself. Is definitely usually a downside into full-monitor game titles. If you adored this write-up and you would certainly such as to receive additional facts concerning clash of clans hack password kindly browse through our web site. You don't want these kind of people using up even a good deal more of your time and after that energy than within some budget place a season clock of your close by to your display exhibit screen to be able to monitor just how long you've been enjoying.

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Nearly as your village grows, the to explore uncharted territories for Gold and Woodgrain effect which are the 8 key resources you may want to expect to require in start of the game ( addititionally there is Stone resource, that your entire family discover later inside our own game ). Through your exploration, you can certainly expect to stumble after many islands whereby that villages happen to you should be held captive under BlackGuard slavery and you results from free Gold money if they are vacant.