Talk:Electroweak interaction

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Unification with Strong Interaction[edit]

Should someone point out that this force has been shown to be identical to the strong force at high enough energy states? —Preceding unsigned comment added by 167.206.78.2 (talk) 6 March 2002

Duh?!!! Thaz something new to me.. can you state some external websites for reference plz? —Preceding unsigned comment added by 62.211.62.220 (talk) 6 March 2002

Identical isn't perhaps the best description. It is believed to unify with strong force to form the hyperweak force at high enough energies in the same way as the elctromagnetic and weak forces unify to make the electroweak force itself. Anyway, this is all somewhat speculative as I don't think there is any fully developed theory of how this works (at least that is successful in producing other aspects of the SM). Additionally, I belive supersymmetry is required to make this unification take place, and that in itself is still a hotly debated area with little or no experimental backup. —Preceding unsigned comment added by Jcobb (talkcontribs) 22:58, 20 February 2004

The unification with the strong force is the subject of grand unified theories. Maybe just a "see also"? —Preceding unsigned comment added by 24.147.149.53 (talk) 19:01, 12 September 2004
Here's one: see electronuclear force. — Herbee 13:06, 29 December 2005 (UTC)

Name of article[edit]

Shouldn't this article be entitled 'Electroweak theory' (or something along those lines) instead of 'Electroweak force '? The other fundamental forces have separate pages for the forces and the theories describing those forces. MP (talk) 10:27, 28 December 2005 (UTC)

Experimental evidence[edit]

If I am not mistaken, there should be discussion of experimental evidence. The article posits the union of the electromagnetic interaction with the weak interaction at energies of 100 GeV. Energies of 200 GeV are not uncommon in accelerators these days. The Tevatron at Fermilab reaches 2 TeV, and the Large Hadron Collider will reach 14 TeV (combined energy). Hu 05:39, 24 March 2006 (UTC)

I second that motion. On the QGP page, it says "The theory of weak interactions has been tested and found correct to a few parts in a thousand". Examples, anyone? Wikipedia brown 06:35, 19 July 2006 (UTC)

To-do List?[edit]

Would someone be willing to make up at least a tenative to-do list for this article? Its kind of a shame that Katie Holmes had a featured article on the main page, but this article, based on Nobel prize winning research is still a stub. I'd do it, but I'm afraid I'm woefully unqualified, being only an undergraduate, with limited experience in this specific segement of high-energy physics. -Davepetr 06:56, 9 April 2006 (UTC)

At least, someone could write something about Quantum flavordynamics (QFD). I think that Electroweak Theory = QED + QFD. I do not know what is the current status of QFD... Urvabara 10:03, 2 November 2007 (UTC)
As a layman I'd like to know how the forces can be unified when different carriers are employed for EM and WNF. --Belg4mit (talk) 04:12, 2 July 2011 (UTC)

Lagrangian diagram[edit]

As the first thing to do, may I suggest someone correct the Lagrangian diagram?

  • The lambda in the Higgs field self-interaction has the wrong sign (and possibly the mu squared as well, although that might depend on convention; these two terms having opposite sign is clearer IMO).
  • The gauge field term coefficient in B in the left-handed field should be 1/2 the coefficient in the right handed field. They are currently shown as identical.
  • Would be nice if the two gauge fields associated the Higgs differential operator were made explicit, as they have been made for the electron and neutrino.

See Quantum Field Theory: A Modern Introduction (1993), ISBN 0-19-507652-4 page 336 by Michio Kaku . I'd make the changes myself, but I'm not sure how.--Michael C. Price talk 12:21, 8 June 2007 (UTC)

Is there a reason we have this as an image? It's not as clear as it would be as LaTeX. --Taejo|대조 12:16, 16 June 2007 (UTC)

I see some much needed updates are being done. Suggestion: that we have a before and after symmetry-breaking version. --Michael C. Price talk 20:09, 10 July 2007 (UTC)
Agreed on the need for a lot of work and on the usefulness of a post EWSB Lagrangian, including the CKM matrix. This was a first pass at getting something that was correct and aligned with standard notation. jay 22:57, 10 July 2007 (UTC)
I made several corrections to the lagrangean before realizing I wasn't logged in. Sorry about that. There are still corrections to be made. Dauto (talk) 17:59, 19 January 2008 (UTC)

What a bunch of formulae (: each of those would deserve an article of its own --82.130.14.173 (talk) 21:55, 4 March 2008 (UTC)

I would suggest someone add the definitions of all the variables involved in the lagrangian, even to the point of saying that the "a" sub/superscripts on the W run over 1,2,3. This would make it more parseable to nonphysicists. —Preceding unsigned comment added by 134.107.13.185 (talk) 14:17, 11 March 2010 (UTC)

Agreed. I'd particularly like to see the substitutions that were necessary to get from the unbroken- to the broken-symmetry Lagrangian. — Preceding unsigned comment added by 130.246.132.177 (talkcontribs) 19:25, 9 July 2012‎ (UTC)
I think that "h.c." means the Hermitian conjugate of the preceding terms (the anti-matter analogue). But I still have not figured out what "g" and "fabc " mean. JRSpriggs (talk) 10:16, 23 July 2012 (UTC)
"g" is the electroweak coupling constant.
"fabc " are the structure constants of the Lie algebra. (i.e. if ga is a basis of the lie algebra (su(2)x u(1) in this case), then [ga,gb]=i fabcgc).
(Also, wow this article is an unreadable mess)TR 10:43, 23 July 2012 (UTC)

────────────────────────────────────────────────────────────────────────────────────────────────────In the before Lagrangian, in this term:

\mathcal{L}_f =   \overline{Q}_i iD\!\!\!\!/\; Q_i+ \overline{u}_i^c iD\!\!\!\!/\; u^c_i+ \overline{d}_i^c iD\!\!\!\!/\; d^c_i+ \overline{L}_i iD\!\!\!\!/\; L_i+ \overline{e}^c_i iD\!\!\!\!/\; e^c_i

I take it that e_i \, varies over the spinors for the electron, muon, and tauon as i=1,2,3. Right?
Similarly, d_i \, varies over the spinors for the down quark, strange quark, and bottom quark as i=1,2,3. Right?
And, u_i \, varies over the spinors for the up quark, charm quark, and top quark as i=1,2,3. Right?
So what do L_i \, and Q_i \, mean? And what does the superscript c mean? JRSpriggs (talk) 21:01, 23 July 2012 (UTC)

Yes, the "i" index appears to enumerate the generation.
The lower case letters (u,d,e) indicate the right-handed fermions (each forms a singlet under the weak SU(2) symmetry). The uppercase letters (Q,L) indicated the left handed SU(2) doublets. I.e. Q=(uL,dL) L=(νL,eL).
As for the c superscript. This is normally used to indicate the charge conjugated field. However, I am puzzled why somebody would use it in the Lagrangian like that. (the sources I checked simply have the plain fields in that location.) It might have to do with specific conventions used by the author.
The c does indeed denote charge conjugation. It's a convention to write it like this so that it's clear that the fields appearing in the lagrangian are all left handed. That is, rather than using the right-handed singlet states, the charge conjugate fields of them are used. It's not hard to argue that it's mathematically (more) valid, but I think it's an unnecessary complication in the equation, and I will remove it in some other edits that I'm making. --Certain (talk) 00:37, 16 August 2012 (UTC)
BTW, if you are trying to figure out what the hell is going on in this Lagrangian, I recommend NOT using this article. Instead pick up a proper book on QFT. For example this Lagrangian is treated in depth in chapter 20.2 of Peskin&Schroeder, Introduction to Quantum Field Theory. It may be though for a lay reader, but at least they explain what their notation means, making it a lot easier to parse than this article.TR 22:04, 23 July 2012 (UTC)

OK---I did a little cleaning up to the lagrangian in the section before EWSB, but when I got to the last two terms I realized this is just a complete mess. It seems odd to include the Higgs VEV explicitly in the higgs term in the section before EWSB. (Maybe even silly to include the higgs term at all, no?). The Yukawa term should also probably be reformatted to just have the coupling of the left- and right-handed fields by the masses, without mention of the Higgs field. This term can then be redescrbed in the post EWSB section as a Yukawa interaction with the higgs field. Overall: this article is a mess. --Certain (talk) 00:47, 16 August 2012 (UTC)

I think that "before EWSB" here is supposed to mean "before expanding the Higgs field around its ground state", i.e. the Lagrangian in its explicit symmetric form. Not, the Lagrangian of the SM before anybody included terms that lead to EWSB.TR 06:35, 16 August 2012 (UTC)
Then it's definitely incorrect to include the vev in that section, because then the field is already being expanded around the vev. It might just be best to scrap almost all of this page and put a link to the higgs mechanism page. (Though I haven't thoroughly read that page, it does appear more correct.) This won't show the specific application of the mechanism to the SM a la Weinberg & Salam, but it will be more valuable as a properly formatted reference.--88.64.10.112 (talk) 22:59, 19 August 2012 (UTC)
The only place where the vev appears in that section is in the potential of the Higgs field, where it is a parameter. That is certainly correct. In fact, despite being badly written as an encyclopedic entry, the treatment given here is mostly consistent with the treatment of this very subject in Peskin & Schroeder.TR 07:33, 20 August 2012 (UTC)

Unified theory of Eletroweak Interactions[edit]

I guess I should also point out that, as it stands, the article implies that the Electroweak theory (EWT) is a theory of the unified electromagnetic and weak interactions. That's an extremely common misconception. Correct would be to call it the unified theory of the electromagnetic and weak interactions. What's the difference? It is an unified theory in the sense that describes both interactions in one single self-consistent framework, but the theory still requires two different coupling constants and as such does not constitute a unification of interactions in the same sense that the term is used when talking about grand unified theory (GUT). Unlike EWT, GUT models do indeed unify three interaction (electromagnetic, weak, and strong) as three different aspects of a single interaction. only one coupling constant is needed. —Preceding unsigned comment added by Dauto (talkcontribs) 18:30, 19 January 2008 (UTC)

Hot Universe?[edit]

How is a hot Universe different than hot matter in a universe? Does the entire universe need to be hot in order to unify the forces or is it enough for only the part of the universe inside a box to be hot in order to unify the forces inside a box? —Preceding unsigned comment added by 76.126.215.43 (talk) 18:57, 9 July 2009 (UTC)

The term "hot universe" refers to a situation where the entire universe contains particles that are "hot" (in this case, posessing energies above the electroweak unification scale). You are correct in noting that any finite region satisfying this condition would also have unification-type behavior occur within that region. That's more or less how particle accelerators attempt to study it (you can consider the colliding particles as producing a very small region in which this condition is satisfied, though there are many other ways of looking at it that are also valid). The whole-universe case is interesting because we're reasonably sure our universe went through a period where it was this hot, which may have left some detectable signature or imprint that tells us about the exact nature of the unification. --Christopher Thomas (talk) 05:14, 10 July 2009 (UTC)

And where are Maxwell's Equations?[edit]

if they can't pull Maxwell's equations out of their particle theory then they have not unified anything at all. It is a gross exaggeration to claim they have unified electro with weak. And without the hypothetical big bang the conditions for their theory don't even exist in nature. Also, what they are really playing with is QED which is just a shell game as Feynman admitted. 173.169.90.98 (talk) 13:37, 20 April 2010 (UTC)

But you can pull ME out of EW theory. --Michael C. Price talk 16:36, 20 April 2010 (UTC)
Do you have a question about the article or are you simply ranting? FYI Maxwell equations come out of the Lagrangian as part of the equations of motion. Dauto (talk) 16:52, 28 April 2011 (UTC)
Maxwell's equations are that 1/4 A^uv A_uv term in the broken Lagrangian. "A" is made up of various combinations of derivatives of the E and B fields. — Preceding unsigned comment added by 130.246.132.177 (talkcontribs) 19:25, 9 July 2012‎ (UTC)

Redirect[edit]

Would anyone like to create a redirect from electroweak unification? 70.247.169.197 (talk) 01:14, 11 August 2010 (UTC)

More on history[edit]

The article needs more on the history of this theory, e.g., what was the first paper written on it and when did it appear? What precursor work was done? What persons/groups were "also-rans"? The theory is part of the Standard Model now, but were/are there any objections to it? Etc. --96.233.94.233 (talk) 02:04, 27 April 2011 (UTC)

Remove reference to W0[edit]

There is a reference to a W0 boson in this article, which is should be a Z0 boson, surely. Just checking in here before I fix it. — Preceding unsigned comment added by 202.36.29.1 (talk) 02:27, 13 November 2012 (UTC)

Do not "fix" it; it is OK as is. If you read the article, you will see that the W0 mixes with the B0 to produce the Z0 and the photon. JRSpriggs (talk) 07:55, 13 November 2012 (UTC)

Does it add same teams twice?[edit]

in the section After electroweak symmetry breaking, the quadratic terms L(K) was including mass terms, which are repeated in the terms L(HV) and L(Y). But they are added up in the first formula. Am I right?--Haojian (talk) 03:34, 18 February 2014 (UTC)

L_K contains only terms with two fields, while L_HV and L_Y contain only terms with more than two, so there can't be repeated terms.-Dilaton (talk) 18:55, 19 February 2014 (UTC)

Could I say that, the mass terms in L_K are interactions between particle fields and Higgs field, in which the Higgs field was regarded as constant and then was packed into the mass values, so contain only two particle fields; on the other hand, L_HV and L_Y contain SAME terms in which the Higgs field was regarded as one of fields, so these teams contain more than two fields?--Haojian (talk) 02:39, 10 March 2014 (UTC)
This is after symmetry breaking, so the masses were established via the Higgs mechanism, and there is now the "seperate" Higgs field.-Dilaton (talk) 06:12, 10 March 2014 (UTC)
The fields can be separate, but the teams are still identity?--Haojian (talk) 07:55, 10 March 2014 (UTC)