Graduate What Are the Missing Links in Enrico Fermi's Beta-Decay Theory?

[Rob S]

In 1933 Enrico Fermi published a paper on his theory of beta-decay. He describes it as a contact force, which means he didn't think there was a mediator as there was for the electrodynamic forces. Somewhere along the line, there must have been someone who suggested a mediating particle such as that proposed by Yukawa for the Strong Force. There is a hint that the Yang-Mill Theory inspired a mediator for the weak force, but I can find nothing until the unification of the electrodynamic and weak forces by Glashow, et al, in the 60s.

I'm looking for that missing link. Any clues would be appreciated.

 

[vanhees71]

I think indeed that Glashow, Salam, and Weinberg had the idea to use "Higgsed" non-abelian gauge theories (1968) with massive vector-boson exchange to make the weak-interaction model renormalizable (although the renormalizability has been proven a bit later by 't Hooft and Veltman in 1971). Of course there's one important episode between Fermi's 1934 theory and the electroweak standard model: In the mid fifties parity violation by the strong interaction has been discovered (Wu's experiment, Ledermann et al's neutrino experiments), and then after some confusion due to the experimental difficulties the (V-A) structure of the exchange currents was established (among various other theorists this is one of the rare papers co-authored by Feynman and Gell-Mann).

A very good semi-popular book on this history is

https://www.amazon.com/dp/0465063829/?tag=pfamazon01-20

 

[bobob]

Actually, Fermi modeled the weak interaction on what was known about the electromagnetic interaction and photon. He assumed it was a contact force because the range of the interaction was very short and therefore it would be, if nothing else, a useful approximation. That it was an approximation was either already obvious or became so, shortly thereafter as Fermi's theory not only didn't describe all weak nuclear decays, it didn't describe most weak nuclear decays. Very shortly after Fermi's theory came Gamow's and Teller's theory which described the decays that Fermi's did not. So, there are now two theories of beta decay, Fermi decay's, which describe coupling to S=0 and Gamow-Teller decays, coupling to S=1.

There was a lot of work done on trying to understand the weak interaction more fundamentally in terms of gauge bosons. Those difficulties were not overcome until the standard model was fairly complete. One of the biggest problems was that using three guge bosons, the Z describing neutral currents, led to predictions of strangeness changing that wasn't observed in experiments.

Here is one article I found on the subject:
https://arxiv.org/abs/0911.0058

 

[vanhees71]

Yep, and that was solved by the "GIM mechanism" (standing for Glashow, Iliopolous, and Maiani), predicting the 4th quark dubbed charm (1970), which was observed in terms of the $J/\psi$ meson in the "November Revolution 1974".

 

[Vanadium 50]

S. Weinberg "A Model of Leptons" PRL19, 21 p.1264 (1967).