# Significance of Higgs model used in Glashow-Salam-Weinberg theory

1. Sheldon Glashow, Abdus Salam, and Steven Weinberg propose the unification of the weak and electromagnetic interaction between elementary particles.
• Glashow, Salam, and Weinberg proposed the model during 1964-1967.

• They were awarded the 1979 Nobel Prize in Physics for their contributions to the unification of the weak and electromagnetic

1. Higgs particle plays an important role for the Weinberg–Salam theory, in order to explain the gauge symmetry breaking $$SU(2)_{weak} \times U(1)_{hypercharge} \to U(1)_{electromangetism}.$$
• Peter Higgs proposed the Higgs model in 1964.

(In 1964 by three groups by Robert Brout and François Englert; Peter Higgs; Gerald Guralnik, C. R. Hagen, and Tom Kibble)

• But Peter Higgs and François Englert had been awarded only much later for the 2013 Nobel Prize in Physics.

So the historical timeline is

1959, Glashow, S "The renormalizability of vector meson interactions." Nucl. Phys. 10, 107.

1959, Salam, A.; Ward, J. C.. "Weak and electromagnetic interactions". Nuovo Cimento. 11 (4): 568–577.

1961, S.L. Glashow. "Partial-symmetries of weak interactions". Nuclear Physics. 22 (4): 579–588.

1964, Higgs et all work on Higgs mechanism, "Broken symmetries and the masses of gauge bosons". Physical Review Letters. 13 (16): 508–09.

1967, Weinberg work on "A Model of Leptons". Phys. Rev. Lett. 19 (21): 1264–66

1979, Glashow, Salam, and Weinberg - Nobel Prize

2013, Higgs et all - Nobel Prize

My question: since Weinberg–Salam theory heavily relies on the Higgs mechanism and Higgs work --- why had Glashow, Salam, and Weinberg been awarded Nobel prizes (1979) much earlier than Higgs (2013)? What are the crucial ingredients in Weinberg–Salam theory independent from the Higgs model? Although that Higgs et all needs to be awarded only after the discovery of Higgs particle in CERN LHC on 8 October 2013, but Weinberg–Salam theory can be confirmed earlier (even the Higgs is not required)?

p.s. The Weinberg's weak mixing angle $$\theta_W$$ again requires the Higgs mechanism, even though $$\theta_W$$ can be verified as a parameter.

• Small remark; the 1959 Glashow paper is not quite right, in today's norms. His significant contribution is the 1961 paper I cite in my answer.... – Cosmas Zachos Nov 23 '20 at 22:31
• How about 1959 Salam, A.; Ward, J. C.? – wonderich Nov 23 '20 at 22:32
• No, that one is a dog! It lacks neutral currents and the entire logic of the SM, which is all there in the 1961 Glashow paper, the mainstay of the SM. Salam and Ward only caught up after 3 years, in 64, by all accounts independently. – Cosmas Zachos Nov 23 '20 at 22:40
• btw I could not understand many of your metaphor usages (including your answer). In the future, could you rephrase it in a poor man's language? (just as simple as possible) What do you mean exactly? Did John Ward contributes a lot or not? en.wikipedia.org/wiki/John_Clive_Ward#Standard_Model – wonderich Nov 23 '20 at 23:05
• As I said, I'd completely drop both the 1959 papers here. Lookig at Weinberg's 1967 paper, he cites Glashow 1961, but Salam 1968 does not, only Weinberg 1967. You might argue he is not giving the Weinberg angle to Glashow, but instead, to Weinberg. I'll stick my neck out and assert Ward is not involved in the neutral current, the heart of the 1979 NP. – Cosmas Zachos Nov 24 '20 at 18:02

This is precisely why this question belongs to HSM.SE with both feet! Your vision of what happened is deeply misleading, possibly requiring time travel. Recall the GWS 79 prize citation:

"for their contributions to the theory of the unified weak and electromagnetic interaction between elementary particles, including, inter alia, the prediction of the weak neutral current."

Glashow's cornerstone Electroweak unification 1961 paper does not know, or care about the 1964 Higgs work. It is mostly on requiring neutral currents for consistency. Salam and Weinberg tack the Higgs mechanism onto it as an extra bell-whistle, and it remains largely irrelevant (fine print) until 't Hooft's 1971 renormalizability work. The (badly misnamed) "Weinberg" angle does not require a Higgs model!

Glashow, as a Schwinger student, believed in some type of dynamical SSB picture, not a Higgs model. Like anybody else, he routinely used sigma models to exemplify the group theory of SSB nonlinear realizations, but, at that time, these were only models, only to be taken seriously in terms of their current and amplitude consequences.

The breathtaking achievement of GWS is the consistent realization of all extant chiral symmetries including the presence of fermion masses induced by Yukawa couplings, given short shrift in modern introductions anxious to sell the Higgs mechanism to novices. It virtually amounts to a magic trick to distract attention.

So, no,

Higgs particle plays an important role for the Weinberg–Salam theory

is not the sine-qua-non you are making it out to be. It's nice to know the exact, original, minimal "Weinberg model" incorporating the elementary Higgs is now promoted to a full theory, beyond model; and the discovery of the remnant boson, (the Higgs boson, proposed in 1966), was a good last chance to celebrate most of the 1964 Higgsers.

But, really, with or without the elementary Higgs boson, the Higgs mechanism should have been celebrated anyway, long before, as 't Hooft's renormalizability proof made it a darling of theorists, and led to the triumph of QFT, celebrated in the 1999 NP. From that point on, a NP for the Higgsers was overdue, waiting for the cherry on the cake, the Higgs boson.

• NB. Edit on crucial features beyond Higgs. Higgsless models survived right up to the discovery of the Higgs, precisely because the Higgs isn't really a live-or-die feature of the SM, but merely the simplest and actual historical option. Even now, SSB chiral gauge invariance with the suitable groups and representations is basically the standard EW theory. To put it dramatically, the elementary Higgs is the only "model" part of the SM, and that's why its confirmation took so long: the rest of the theory doesn't much care about it!
• thanks very much, voted +1, it helps – wonderich Nov 22 '20 at 18:47
• I like your storytelling answer. But can you also be direct on this question "What are the crucial ingredients in Weinberg–Salam theory independent from the Higgs model? that also makes Electroweak unification complete? just by the mathematical facts?" Can you add an answer to this at the end or beginning? – wonderich Nov 22 '20 at 18:51
• Thanks! Wiki and ref show In 1964, Salam, Ward and Weinberg had the same idea, but predicted a massless photon and three massive gauge bosons with a manually broken symmetry. --do you know why Ward is not awarded Nobel prize? – wonderich Nov 23 '20 at 1:06
• No; there is lots of legitimate discussion about that, assuming you mean this one. The point is, Higgsless, Glashow preceded them all, with clarity and power. Then S & W put in the Higgs. In his Nobel lecture, Salam gives an impression of how parallel such slapdash efforts were by many; he surpassed his joint work with Ward by the additional 1968 work incorporating the Higgs mechanism, inextricably entwined with Weinberg and their joint work on Goldstone physics. – Cosmas Zachos Nov 23 '20 at 1:45
• Here is a (private) copy of the Salam paper. But, in fact, the NP is not awarded for specific papers, but for seminal work contributing to a picture decisively. As Glashow put it, contributing "threads to a tapestry". – Cosmas Zachos Dec 28 '20 at 23:49

It is called verification from experimental results.

The GSW theories fitted mathematically the observed particle zoo symmetries and explained the approximate symmetries seen in the data.

The Higgs model at the time of award was not the only model for getting the results of symmetry breaking, it could be a different process inducing the breaking , as in techincolor, where a composite particle was proposed for the higgs.

The specific higgs model used in GSW theories had a field for the Higgs, which means in quantum field theory that an elementary particle should exist , and it needed its discovery in order to uniquely define the Higgs mechanism with nature.

All experiments were looking for a Higgs particle , but their energy at the time was too low.The LEP accelerator just missed the mass found in LHC.

• thanks very much, voted +1, it helps – wonderich Nov 22 '20 at 17:01
• Thanks! Wiki and ref show "In 1964, Salam, Ward and Weinberg had the same idea, but predicted a massless photon and three massive gauge bosons with a manually broken symmetry." --do you know why Ward is not awarded Nobel prize? – wonderich Nov 23 '20 at 1:09
• probably he was a graduate student and his thesis was assigned by either weinberg or salam – anna v Nov 23 '20 at 5:14
• Thanks it will be nice to know the evidence if this is the case ... Lol – wonderich Nov 23 '20 at 15:02
• my guess was wrong en.wikipedia.org/wiki/John_Clive_Ward . I suppose one has to read the nobel awarding reasons, usually they pile it up. Particularly see this paragraph en.wikipedia.org/wiki/John_Clive_Ward#Personal_life_and_death – anna v Nov 23 '20 at 15:39

In the development for the theory of weak interactions one important papers was the 1967 paper of Weinbergs where he combined a theory of leptons with a spontaneous breaking of the SU(2) x U(1) local or gauge symmetry. A dis Salam had done very similar work.

It was not immediately taken notice of because of the lack of experimental verification. However, an accelerator in Chicago was being under construction that would push the boundaries of what energies could be probed. By 1971 work on it had finished and it discovered the neutral currents.

As we can see here, what was important was not only theory - but also experiment. The experimental verification of the Higgs was way out of reach, taking until the second decade of this century before it was shown that it existed. Hence the delay in awarding Higgs a Nobel prize (with others).