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This is a soft question so may not be suitable for this site.

The LHC famously discovered the Higgs boson several years ago, but also seems to have ruled out several hoped for versions of supersymmetry (pushing the mass range for the supersymmetric partners higher). One general problem experimental particle physicists seem to have at the moment is that it is difficult to find physics outside the standard model.

My question is: from an outsider’s perspective, the Higgs seemed as speculative as, for example, supersymmetry. We had no direct evidence for the Higgs field outside of a need for consistency in the model so that we could explain fundamental particle’s mass - but supersymmetry also purported to explain defects in the theory, resolving hierarchy problems.

Why was the Higgs included in the standard model but those other parts which had no direct evidence were not?

Given the fact that we have actually found evidence for all the pieces of the standard model, but nothing incredibly compelling for proposed extensions, there surely must be something objective which sets it apart?

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Without the Higgs Boson, the W and Z boson would be predicted by the standard model to have 0 mass. Experimentally we knew that was wrong.

Long story short, a slight adjustment to the standard model could yield the exact right masses for the W and Z bosons, but a consequence of that adjustment that yielded the right masses was that there must also be a Higgs Boson. There was no way to make an adjustment to get massive W and Z bosons without creating another particle in the theory.

It was included in the SM because it was necessary to get the SM to work and be self-consistent (and now we know for good reason - because it's there!) Supersymmetry is not needed for the SM to be accurate and self-consistent.

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The Higgs boson is a result of the Higgs Mechanism included in the Standard model . Because the SM is a quantum field theory, it is as a result of the HM that a boson particle should exist corresponding to the Higgs field .

In supersymmetry the table of particles is taken as an experimental observation and treated axiomatically , and the mathematics of supersymemtry :

Supersymmetry predicts a partner particle for each particle in the Standard Model, to help explain why particles have mass

The link describes the difference.

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  • $\begingroup$ My question is more around why the Higgs mechanism was included in the standard model whereas other proposal were not. I will look at your link to see if it clarifies matters. $\endgroup$
    – Nethesis
    May 20, 2023 at 8:16
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    $\begingroup$ @Nethesis the HM was included in the SM because without it the particles in the table would be massless and the SM would not fit the data. In supersymmetry the reverse happens, the particles are assumed to be massive . $\endgroup$
    – anna v
    May 20, 2023 at 9:27

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