Imagining a Higgsless Universe

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Discussion Overview

The discussion explores the implications of a hypothetical universe governed by the Standard Model without the Higgs mechanism. Participants examine how the absence of the Higgs field would affect particle masses, interactions, and the overall structure of the universe, focusing on theoretical aspects and speculative scenarios.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that in a Higgsless universe, all elementary particles would be massless, leading to significant changes in particle interactions and the nature of forces.
  • It is proposed that unbroken SU(2) would result in two new forces, with left- and right-fermions treated as different particles, and antiparticles defined accordingly.
  • Some participants discuss the potential for isospin charges and their implications for particle interactions, noting that left-fermions would form isospin doublets.
  • Questions are raised about whether the SU(2) interaction would exhibit asymptotic freedom and confinement, and whether leptons could form composite particles termed "leptohadrons."
  • Another participant corrects their earlier claim regarding isospin charges, suggesting a revised understanding of how neutrinos and electrons fit into the proposed framework.
  • It is noted that the Higgsless Standard Model would have only three parameters related to gauge coupling strengths, with all fermion masses and Yukawa couplings absent.
  • A participant shares insights from a discussion with Chris Quigg, emphasizing that the removal of the Higgs coupling leads to complex consequences for particle masses and interactions, including the emergence of non-zero masses for certain particles due to QCD effects.

Areas of Agreement / Disagreement

Participants express a range of ideas and hypotheses, with some corrections and refinements to earlier claims. There is no consensus on the implications of a Higgsless universe, and multiple competing views remain regarding the nature of particle interactions and masses.

Contextual Notes

Limitations include unresolved assumptions about the nature of particle interactions without the Higgs mechanism, the dependence on definitions of isospin and hypercharge, and the implications of QCD in a Higgsless scenario.

  • #31
Got reminded of this thread from https://www.physicsforums.com/threa...-second-third-generation.890021/#post-5599190

Vanadium 50 said:
Step 1: set the Higgs coupling to the W and Z to zero. The W and Z masses don't go to zero: they go to about 30 MeV because they still get a QCD mass from the quark condensate.

Step 2: Let's set the Higgs couplings to the quarks to zero. This should set all the 0- masses to a 36-fold degenerate zero, because they are all Goldstones. Other mesons will still be massive, as will the baryons, because their mass is governed by LambdaQCD and not the quark current masses. Surely that will set the W and Z masses to zero. And...now they weigh about 100 keV.
What exactly do you mean by step 1? The Higgs will still be an SU(2) doublet and the coupling is fixed by the SU(2) coupling constant because the interaction term originates in the covariant derivative of the kinetic term for the Higgs field. Putting the Higgs coupling to the SU(2) gauge bosons to zero would imply putting the SU(2) coupling constant to zero and the SU(2) part of the theory would then be free and meaningless. If you make the Higgs an SU(2) singlet, clearly it will no longer couple to the SU(2) gauge bosons, but then you have fundamentally changed the field content of your model. On the other hand, if you do that you will no longer have a scalar doublet that you can use to create the Yukawa couplings that you want to turn off in step 2.
 
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  • #32
The steps are not intended to be viable, consistent and renomalizable theories on their own. They are there to illustrate the consequences in a simple way. Think of it like removing and then reinserting the corilois force in discussing classical mechanics.
 
  • #33
I don't see why it is interesting to discuss a model where a Higgs boson/field does not exist when there is now good evidence that it does.
 
  • #34
rootone said:
I don't see why it is interesting to discuss a model where a Higgs boson/field does not exist when there is now good evidence that it does.

Well, depends of your view of the goals of discussing. Towards publication of a pheno paper, it is sort of absurd. Towards learning or even as advanced undergraduate work, it is valuable.
 
  • #35
rootone said:
I don't see why it is interesting to discuss a model where a Higgs boson/field does not exist when there is now good evidence that it does.

It helps illustrate the role played by the Higgs.
 
  • #36
We also are happy to let our students play with several hypothetical scenarios in order to understand the theory better. I see no reason why we should not do the same ourselves.
 

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