Is the top quark stable in the absence of the Higgs field?

In summary: This depends on the field content of that universe. If you just removed the Higgs field from the SM, yes - you could tell that there were three generations. You could not tell the generations apart.
  • #36
kodama said:
that's what i am wondering about

a hypothesis that the reason second and third generation fermions are heavier than first and interact more strongly with the higgs field there is a higgs-charge that is a charge in the sense of a charge related to a gauge symmetry

Yukava couplings are partially analogous to charges. The difference is that charges related to a gauge symmetry manifest themselves as a constant in the gauge covariant derivative's formula, and this constant is the same for all particles. For QED, the constant is the electron's charge.

Yukava couplings are constants too, but they are _different_ for every higgs-to-fermion coupling. No evidence so far exists that they are multiples of some fundamental, minimal "charge".

The reason for this difference is that coupling terms in Lagrangian for fermion-to-spin1-boson coupling and fermion-to-spin0-boson coupling have different forms.
 
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  • #37
Orodruin said:
If there is no Higgs the Z is massless and does not decay (well, truth with modification).
I don't get that part, why wouldn't Z decay?
 
  • #38
ChrisVer said:
I don't get that part, why wouldn't Z decay?
How many massless particles do you know that decay?
 
  • #39
Orodruin said:
How many massless particles do you know that decay?
I know 1 massless particle out of the 1 massless particles there which can decay (well not alone)...
 
  • #40
ChrisVer said:
(well not alone)...
So, not a decay.
 
  • #41
This means that in a Higgsless universe you would not have 3 neutrino flavors also?
 
  • #42
You would still have three flavors. If you can distinguish between different neutrino types depends on the mechanism that leads to neutrino masses, but the different masses (if applicable) would be the only difference you could see.
 
  • #43
mfb said:
You would still have three flavors. If you can distinguish between different neutrino types depends on the mechanism that leads to neutrino masses, but the different masses (if applicable) would be the only difference you could see.
Many (not all, but I would say a majority of) neutrino mass models give rise to neutrino masses through the appearance of a Weinberg operator after integrating out some heavy states. Without the Higgs, such operators do not exist.
 
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  • #44
in a higgless universe, what would happen if a tau interacts with a positron?
 
  • #45
kodama said:
in a higgless universe, what would happen if a tau interacts with a positron?
What happens in this universe (Higgsfull) when a tau interacts with a positron?
I don't know, is the Lepton number also associated with the existence of the Higgs?
 
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  • #46
ChrisVer said:
What happens in this universe (Higgsfull) when a tau interacts with a positron?
I don't know, is the Lepton number also associated with the existence of the Higgs?

i was going to ask that to
 
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