Breaking SU(3)xU(1) to SU(2) Exercise: A Search for Solutions

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Discussion Overview

The discussion revolves around the exercise of breaking the gauge group SU(3)xSU(2)xU(1) down to SU(2), exploring the implications of Higgs content and the nature of the resulting U(1) symmetry. Participants consider various theoretical frameworks, including Kaluza-Klein compactifications and dynamical breaking in quantum chromodynamics (QCD).

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants seek guidance on the specifics of the exercise, particularly regarding the Higgs content and the implications for the U(1) symmetry that emerges after breaking.
  • There is a suggestion that the resulting U(1) may not necessarily correspond to the nonchiral U(1) of electromagnetism, depending on the nature of the symmetry breaking.
  • One participant proposes a connection between the gauge symmetry breaking and compactifications of extra dimensions, hypothesizing a relation between the Standard Model and a compactification from higher dimensions to a lower dimension.
  • Another participant notes that breaking gauge symmetries requires specific compactification techniques, such as using orbifolds rather than circles, and emphasizes the importance of boundary conditions for gauge bosons.
  • There is skepticism about finding a solution online, with a suggestion that this exercise may not be standard in textbooks.
  • A question is raised about the relevance of examples from dynamical breaking in chiral QCD, although it is noted that this scenario does not involve a Higgs field.

Areas of Agreement / Disagreement

Participants express differing views on the specifics of the symmetry breaking process and the nature of the resulting U(1) symmetry. There is no consensus on the best approach to the exercise or the existence of readily available solutions.

Contextual Notes

Participants mention the need for clarity on assumptions related to compactification methods and the role of the Higgs field in the context of gauge symmetry breaking.

arivero
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Can anyone provide a pointer to the exercise of higgs breaking SU(3)xSU(2)xU(1) down to SU(2)? I expect it to be solved somewhere in the web...
 
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It should be pretty easy. What is it, exactly, that you're interested in?
 
BenTheMan said:
It should be pretty easy. What is it, exactly, that you're interested in?

First, to check I am guessing it right. The Higgs content, etc. And what happens with U(1): do we forcefully get the nonchiral U(1) of electromagnetism, or does it depend of the breaking?

As you say, it is easy and one could expect to find it in some web of solved QFT exercises.

My long shot is to relate the breakings with the compactifications of extra Kaluza Klein dimensions. I would expect Standard Model ---> SU(2) to correspond with a compactification from dimension 10 or 11 to dimension 6.
 
arivero said:
First, to check I am guessing it right. The Higgs content, etc. And what happens with U(1): do we forcefully get the nonchiral U(1) of electromagnetism, or does it depend of the breaking?

Well, you don't necessarily have to get U(1) EM, because that is a very specific linear combination that survives.

As you say, it is easy and one could expect to find it in some web of solved QFT exercises.

My long shot is to relate the breakings with the compactifications of extra Kaluza Klein dimensions. I would expect Standard Model ---> SU(2) to correspond with a compactification from dimension 10 or 11 to dimension 6.

Well, it depends on what you're compactifying on. You can't break gauge symmetries if you compactify on a circle---you have to compactify on an orbifold. Then you have to figure out where the gauge bosons live, and how to assign them boundary conditions.
 
We'll just have to work it out, I doubt that you'd find it online anywhere. It seems like a non-standard textbook exercize.
 
Hello,

don't you have similar example from dynamical breaking of chiral QCD ?
 
Barmecides said:
Hello,

don't you have similar example from dynamical breaking of chiral QCD ?

Hmm, but there is not Higgs field involved there, is there? In any case I will check Donoghue et al. :smile:
 

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