Fermi's interaction

In particle physics, the Fermi interaction is an old explanation of the weak interaction. Enrico Fermi suggested this theory, in which four fermions interact directly with each other ( hence the name four- fermion interaction). It is, for example, to decompose directly in a position to a neutron (two down quarks and an up quark ) into an electron, an antineutrino and a proton ( two up quarks and a down quark ).

The Fermi interaction is described remarkably well by Feynman diagrams of lowest order ( tree level). Loop diagrams can not be reliably calculated because the Fermi interaction is not renormalizable. As a solution, it is replaced by a more complete theory - describes the exchange of a W and a Z boson as in the renormalizable electroweak interactions.

Before the electroweak theory and the standard model were set up were George Sudarshan and Robert Marshak and irrespective of Richard Feynman and Murray Gell-Mann is able to determine the correct tensor structure of the four- fermion interaction: Vector minus pseudo vector, V - A.

Fermikonstante

The strength of the Fermi interaction is determined by the Fermi coupling constant GF. In modern notation:

It is

• The reduced Planck constant
• C is the speed of light
• MW the mass of the W boson.