Talk:Higgs boson

Intro edit - eyeballs?

Any chance of eyeballs on this edit I made [1]? I've tried to put the explanation of the particle first, then the explanation of its name. I really wanted to link two sentences or reduce repetition, but couldn't find a good way to do so. Best I have as an alternative so far is:

"The existence of a Higgs field and its associated Higgs boson would be the simplest of several ways to explain how certain elementary particles have mass. The Standard Model says these particles gain mass by interacting with the Higgs field, which has non-zero strength everywhere, even in otherwise empty space."

Not really brilliant prose. Improvements? FT2 ^{(Talk | email)} 09:54, 14 July 2012 (UTC)

Readable sources (for laymen) about the connection between Higgs field and Higgs boson are:

• Flip Tanedo: Who ate the Higgs?; Helicity, Chirality, Mass, and the Higgs
• Matt Strassler: The Higgs FAQ 1.0; The Standard Model Higgs

Maybe something could be used to simplify or better formulate the introductory parts. --D.H (talk) 10:05, 14 July 2012 (UTC)

That's the best formulation/prose I've seen so far for the lead. Well done. Dickdock (talk) 11:47, 14 July 2012 (UTC)

The intro has developed an error: "The Higgs mechanism is the simplest of several proposed ways to explain why certain other elementary particles have mass". That's incorrect. The Higgs mechanism is essentially considered confirmed; the question then is what causes the mechanism to happen. It's the Higgs field and its related force carrier that is the correct subject of the clause "is the simplest of several proposed ways to explain" how that mechanism is realized. FT2 ^{(Talk | email)} 20:52, 15 July 2012 (UTC)

Incidentally, "force carriers" usually refers to the spin-1 bosons that mediate the gauge interactions (i.e. W, Z, photon and gluon). I've never seen the Higgs boson referred to in that way. Ptrslv72 (talk) 22:36, 15 July 2012 (UTC)

Why do physicists dislike the God Particle?

Currently, the introduction states:

Although the proposed particle is both important and elusive, the epithet is strongly disliked by physicists, who regard it as misleading exaggeration[10][11] since the crucial focus of study is to learn about the Higgs field - the boson is a means to that end - and because the field rather than the boson theoretically gives mass to some other particles.

I am really unconvinced by the explanation since the crucial focus..., which sounds as if the reason why physicists dislike the epithet was that it does not do justice to the distinction between Higgs boson and Higgs field. I don't think this is the case: as both references 10 and (especially) 11 make clear, the main reason why physicists don't like the name is that it lends religious overtones to a subject that has nothing to do with God. Unless somebody can provide sources in support of the current explanation of the dislike, I would be inclined to remove it. Cheers, Ptrslv72 (talk) 16:26, 16 July 2012 (UTC)

What's missing is the "religious overtones" sense (the implication that "this is the pivotal and mystical particle that if it exists, explains all"). The rest is valid, but this aspect is not present at all, and should be made clear. FT2 ^{(Talk | email)} 12:33, 17 July 2012 (UTC)

I am not sure that "the rest is valid". The way the sentence is written now, it almost sounds as if "God field" would be ok whereas "God particle" is not ok. The distinction between field and particle is important elsewhere in the lead, but it is not the reason why physicists dislike the nickname (this appears to be just an interpretation of yours which is not supported by the references). Ptrslv72 (talk) 12:58, 17 July 2012 (UTC)

Tried to fix this. FT2 ^{(Talk | email)} 13:40, 17 July 2012 (UTC)

I am missing my copy of Lederman's book The God Particle that started all this. It's a very good book, however, and I recommend it. But let us remember that it was written in 1992 or so when there was a real possibility that the Superconducting Supercollider (SSC) would be cancelled in Texas (as eventually it indeed was), and the book was written in part to raise popular awareness of the physics that the SSC was supposed to produce, which was (of course) the Higgs. Lederman's later comment that he wanted to call it the "godamn particle" should be taken in light of Lederman's sense of humor and playfulness. He's a raconteur if nothing else, and not beyond re-spinning this. Originally the book argued for finding Higgs as a way that the common US taxpayer (most of whom are religous) could make a connection with the ways of God-- by paying for the SSC!

As I remember, in Lederman's book this included not only an argument about the fundamental particles and their mass, but also the Higgs' role in the inflation of the early universe, as originally postulated by Guth in 1980. So Higgs would have had a major role in explaining creation, too. That's god-like. In 1992 (the book published in 1993) I'm not sure it had yet been determined that the Higgs field could not have caused Guth's inflation, as Guth originally had suggested in 1980 that it had. So THAT 1992 reason for calling Higgs "The God Particle" has (by now) been forgotten. Somebody is going to have to read Lederman's book to see (again, my copy is on loan to somebody). However, it's highly referenable, since Lederman is the guy who is to blame for this term. But the Higgs boson's supposed role in cosmic inflation, plus Lederman's desire to have Believers pay for the SSC, surely both played a role in his choice of a moniker for the thing. And those facts should go in Wikipedia. SBHarris 17:33, 17 July 2012 (UTC)

Since the article talks about the source of the common name 'the god particle', it should mention Lederman has said he wanted to call it the 'goddamn particle'. Besides the author good reference to cite is an NPR interview with Dr. Victoria Martin of Edinburgh University [2] (who studied under and worked with Higgs and has current research at CERN):

SIEGEL: I want to ask you about this particle's nickname, the "God particle." What did Higgs, who I've read is an atheist, think about the nickname the "God particle"?

MARTIN: I'm sure - I actually haven't ever asked him this directly, but I'm sure he doesn't like it. Almost all particle physicists detest that name. It was actually Leon Lederman, who's a Nobel laureate, that came up with it. But he was trying to call it "that goddamn particle," and that wasn't allowed by the publishers so it became the "God particle." So the name stuck and I think it's fine because then people know what we're talking about. But secretly, all of us hate the name, the "God particle." [3]

And here is a quote from Higgs on the subject:

"...Higgs himself is no fan of the label. "I find it embarrassing because, though I'm not a believer myself, I think it is the kind of misuse of terminology which I think might offend some people."

It wasn't even Lederman's choice. "He wanted to refer to it as that 'goddamn particle' and his editor wouldn't let him," says Higgs."[4]

Klolo9 (talk) 05:23, 19 July 2012 (UTC)

Possible different article split?

if the Higgs boson is confirmed, what would people think about splitting this article into Higgs field and boson, and a new article Search for the Higgs boson. The search itself is a very substantial topic, covering issues such as "why does it matter" and "what is the history" and a great amount of detail that really is not much to do with the particle itself. It might be easier to have an article on the particle/field with a summary style section on the search and its background. If it's not found then the particle is hypothetical and no need to split it really as the only "story" is the search. FT2 ^{(Talk | email)} 23:46, 17 July 2012 (UTC)

seems like a good idea to me. I would also suggest making a timeline of the search for the higgs boson. Amphicoelias (talk) 10:39, 18 July 2012 (UTC)

I don't think a split is essential at this time. Although in the long run an separate Search for the Higgs boson could be useful, especially if we want to include more detail on the search than we currently do. As for renaming this article to Higgs field and boson, I don't really see the need that badly. The current title "Higgs boson" can already refer to both.TR 10:51, 18 July 2012 (UTC)

I think that when the dust settles, the “Experimental search” and “Timeline of experimental evidence” sections ought to be culled according to the will-people-still-be-interested-in-this-in-ten-years criterion. But I'm undecided whether the excess material should be removed altogether or moved to a sub-article. A. di M. (talk) 22:43, 20 July 2012 (UTC)

The experimental search information should definitely stay somewhere. The Higgs went the longest from prediction to discovery of any particle (44 years, twice the top quark, easily more than the tau neutrino's 26 years). This difficulty has made it the last SM particle to be discovered and has become a significant part of its identity. I like the idea of moving details to a different article, though. Law of Entropy (talk) 05:55, 5 August 2012 (UTC)

Of course it will still be interesting after 10 years, from a science history perspective if nothing else. I think a separate article about the search is a good idea as well. 85.230.137.182 (talk) 21:09, 9 September 2012 (UTC)

I have gone ahead and started a separate article Search for the Higgs boson. I'll update it with some of the earlier history of the search as I have time. Once it has reached a decent state we may want to consider trimming the experimental search section here down.TR 20:55, 20 August 2012 (UTC)

Some subtleties with regard to what particles are massless without a Higgs field.

There are some subtleties with regard to the masses of particles, which seem to be confuse some editors here:

• The particles that acquire a mass through interaction with the Higgs are: all elementary fermions (with possible exception of the neutrinos) plus the the W and Z gauge bosons.
• However not all these particles will be massless if there were no Higgs field in the Standard Model.
• The reason for this that if the quarks are massless, the strong dynamics of QCD will break the electroweak symmetry with the pions acting like goldstone bosons (and become the longitudinal modes of the W and Z bosons, which acquire a mass.)
• Consequence: If there were no Higgs field in the SM, all elementary fermions would be massless, but the W and Z bosons still would have a mass.

Now this does not need to be discussed in this article. However, it does force us to be very careful in phrasing sentences about which particles acquire mass and which don't. TR 15:27, 18 July 2012 (UTC)

Well, if right-handed neutrinos have a Majorana mass they would still have it without the Higgs mechanism (though without the Yukawa coupling between them, left-handed neutrinos, and the Higgs field, they would couple with nothing at all and so there'd be no way to make or detect them). A. di M. (talk) 07:30, 19 July 2012 (UTC)

But the SM does not have right-handed neutrinos. But, yes neutrinos are another point of subtlety, where we simply do not know yet how they get a mass.TR 08:35, 19 July 2012 (UTC)

Well, the most straightforward thing would be adding right-handed neutrinos (with all quantum numbers equal to zero) and couple them to left-handed neutrinos via Yukawa coupling, the same way it's done with up-type quarks, with the PMNS matrix as the analogue of the CKM matrix. A. di M. (talk) 13:17, 19 July 2012 (UTC)

Yes, it would, but there are alternatives. Neither are in the SM though.TR 13:38, 19 July 2012 (UTC)

Where would it go in the Standard Model "grid"?

While the results so far only indicate a boson of some sort was found, the news (whatever it's worth) tells me it's likely to be the Higgs boson. In the Higgs Boson#Theoretical properties section, the interaction diagram includes the Higgs boson. And in the Higgs Boson#General description section, there's a sidebar for Template:Standard model of particle physics, which doesn't include the Higgs boson, which is reasonable since it hasn't been confirmed yet. But given how long the search has been, there must already be some sort of arrangement physicists have in mind. What would it look like? The only thing like that I've seen is on Wikipedia is at Standard Model#Higgs boson. I think it would be useful to have a similar (or same?) diagram on the Higgs boson article, to clarify to laymen such as myself how it is expected to fit, generally. 24.57.210.141 (talk) 23:52, 18 July 2012 (UTC)

As far as I know, the fermions can be organised into three generations, with one pair of quarks and one pair of leptons for each generation. But there is no arrangement for the bosons that I'm aware of, the current table just lists them alongside the fermion generations because it fits visually, not because it also fits through physical properties. So it doesn't really 'fit' anywhere in particular, and the question of where to add it to the table is really one for Wikipedia editors to answer, not scientists. CodeCat (talk) 00:38, 19 July 2012 (UTC)

Technical request - what's correct here?

@TimothyRias - Following some recent edits of yours I edited the rest of the intro to bring it into line, and you've reverted that to what you describe as an "error free" version. Since my edits reflected your own, can you take another look and figure what we ought to be saying:

1) You edited: from: "the Standard Model says some particles that have mass would be massless" to: "the Standard Model says that elementary fermions such as quarks and electrons would be massless".

If this is correct then (a) other references to "some particles" or "elementary particles" should also be edited to "elementary fermions", and (b) the assertion should be cited. You reverted.

2) Also your comment in a previous section describes the subtleties in this area - which particles "get mass" and what that means, to what extent it's accurate. Does this imply that the edit you made from "some particles" or "elementary particles" to "elementary fermions" in the mass footnote is insufficiently precise as well, and should also be firmed up?

If so could the "terminology" section be a good place for that? As it covers "basic terms knowledge needed for the topic" - maybe the Higgs mechanism paragraph could outline what gains mass from HM?

3) Again the mass footnote, what's actually known at this point where HF is not proven, is that a HM exists. It's suspected to be due to one or more HF but this isn't proven yet and other ways to generate a HM exist or could exist. The mass note stated "Without some source of the Higgs field, the Standard Model says..." but this isn't the best note on the issue. It essentially deals with the case that SM/HF is correct - but at present it need not be.

The more useful explanatory note here isn't to write "without HF, SM says these particles would be massless" which is accurate but over-limited and merely a comment on one specific solution not yet proven (although believed to be correct). The better comment is that "without some source of HM, any current model will say these particles are massless".

Ie, the more pointed requirement is to make clear in the footnote, that a criterion for any credible theory (and this seems to apply to all theories currently deemed credible) has to provide specifically, a source of HM. The existing wording sidesteps that core point by just discussing what SM requires, but at a point where SM is itself one of a number of theories and the whole aim is to find if SM or something else is right. In these circumstances it's better to explain what any candidate theory of particle physics has to provide for - namely it must show some viable explanation for the source of HM.

4) As noted earlier in talk page points out "multiple HB means multiple HF" so we can't say it's just a single HF. I edited the lede to reflect this, from: "The leading explanation is that these particles acquire mass by interacting with the Higgs field, which has non-zero strength everywhere" to: "The leading explanation is that one or more Higgs fields exist, having non-zero strength everywhere, and these particles gain mass by interacting with it". You reverted to "a field" (singular).

While basic SM is the current explanation, if it's correct that some quite favored SM extensions predict multiple HF, then the lede should probably say "one or more". It wouldn't hurt and would then be much clearer that this could be the case for some outcomes that involved a HB (ie SM extensions) and it wouldn't surprise the reader when we later say there could be multiple HF even if HB was found.

Can you take a look at these? Thanks :) FT2 ^{(Talk | email)} 00:40, 19 July 2012 (UTC)

1) See my comment above. Although the Higgs field gives mass to all massive particles, not all particles become massless if there is no Higgs field. The change you made was incorrect.

2)No, my remark in the mass footnote is precise. (Without a Higgs field all elementary fermions are massless according to the SM.)

3)There is a problem with saying "without some source of HM". The SM model already has a source of HM build into it. If the quarks are massless, the strong dynamics of the quarks will break the Electroweak symmetry on their own (however the W and Z would be much lighter (~10 MeV) than observed (~100 GeV)). Since the quarks cannot get a mass without breaking the electroweak symmetry, this means that there will always be a source of the Higgs mechanism.

Moreover, even if there is a source of the HM, if it does not couple to the fermions they will still be massless. E.g. this is the case in the SM without a Higgs field.

4)I think including the possibility of multiple Higgs is in the lede over complicates things. It generally makes the statements much harder to digest. I think we are pretty safe in saying the leading explanation is a single Higgs field (even if it is not really favoured that much). We can discuss possible extensions with multiple Higgses, or composite Higgses, or whatever further down in the article, where there is more room to provide the appropriate context.

TR 07:27, 19 July 2012 (UTC)

Update - I've tried to improve a couple of technical points (I'll come back to others later perhaps). Specifically as far as I can understand, other mass generation mechanisms exist (the article note refers to these already) and the term "Higgs mechanism" in the broadest sense is a general term for symmetry breaking mechanisms. For example, if it were the only kind of symmetry breaking mechanism them statements found on physics pages on the theme of "HM in SM almost always refers to EWSB" would be redundant, as it couldn't possibly refer to anything else. From the Higgs mechanism article (nicely updated - good work!) I draw the point that in the Standard Model, HM/EWSB is responsible specifically for the mass of certain gauge bosons, but not all of them. On the assumption that's correct I've also edited this article a bit. Can someone check these are technically ok? Thanks. FT2 ^{(Talk | email)} 16:22, 6 August 2012 (UTC)

I've adjusted your edits a bit. I'll try to explain here.

The Higgs field does 2 things in the Standard Model:

1. It breaks the SU(2)xU(1) electroweak gauge symmetry to the U(1) gauge symmetry of electromagnetism through the Higgs mechanism. In the process giving mass to the W and the Z bosons, the weak gauge bosons. (All other gauge bosons are massless)
2. By interacting with the fermions, the Higgs field gives mass to the elementary fermions. (i.e. all particles that interact with the Higgs have mass, and all elementary particles with mass, get that mass through interaction with the Higgs.(with a possible caveat for right handed neutrino's, but they are not part of the SM in the first place.)) Somewhat confusingly, this second part is also sometimes referred to as the Higgs mechanism (because it is made possible by the Higgs field being non-zero in the ground state.

Note that the above is not true for all possible sources of electroweak symmetry breaking. For example, QCD with massless weakly interacting quarks, also breaks the EW symmetry. In that case, the corresponding goldstone bosons are the pions, and they get absorbed by the weak gauge bosons to provide them with mass. However, the fermions do not get a mass. Vanilla technicolor has the same problem.

I think for this article (and especially the lede) we should avoid getting side tracked by discussing what is called the Higgs mechanism, and what is not. Instead the focus should be, what does the Higgs field do? (i.e. give mass to all massive elementary particles).TR 11:32, 7 August 2012 (UTC)

Article should mention the Higgs singlet

The article should mention the Higgs singlet. — Preceding unsigned comment added by Ocdnctx (talk • contribs) 00:48, 27 July 2012 (UTC)

Higgs production

I modified TR's entry on Higgs-strahlung because I thought that the term refers to the process in which you still have a gauge boson in the final state (i.e., the gauge boson emits a Higgs, it does not decay into a Higgs - indeed "strahlung" is German for "radiation"). However, on a second thought, it might well be that the process in which a real Z decays into a Higgs boson and a fermion pair was also referred to as Higgs-strahlung in the nineties (i.e., at the time of LEP1). If that can be proved with a reliable source we can restore TR's sentences on the subject. Ptrslv72 (talk) 09:35, 27 July 2012 (UTC)

I think you are right. Good call.TR 09:57, 27 July 2012 (UTC)

ATLAS 5.9sigma, CMS 5sigma

ATLAS published new results and improved the local significance at 126 ± 0.4 (stat.) ± 0.4 (sys) GeV/c² to 5.9sigma

http://arxiv.org/abs/1207.7214

And CMS reached a local significance of 5sigma at 125.3 ± 0.4 (stat) ± 0.5 (sys) GeV/c²

http://arxiv.org/abs/1207.7235

Submitted to Physics Letters B. --D.H (talk) 08:31, 1 August 2012 (UTC)

Correct capitalization?

Hi, nuclear physics graduate student here. I'm just wondering why the particle is typed "Higgs boson" instead of "higgs boson." I mean, bosons in general are named after a scientist, just like the "higgs." Should we be typing it in lowercase to remain consistent? If Wikipedia moderators agree, could we change the article's title to higgs boson? Thanks. — Preceding unsigned comment added by 107.4.189.194 (talk) 23:57, 4 August 2012 (UTC)

It is standard practice in the literature to capitalize Higgs. As it should be since Higgs is a proper name. Some other examples that follow that rule and are likely familiar are Feynman diagram, Dyson series, Weinberg angle. There are many such examples. Dauto (talk) 03:58, 5 August 2012 (UTC)

My experience is that complete names used as separate words retain their capital letters, and compound or derived terms start to lose them. Therefore, we have bosons that follow Bose statistics, and Goldstone bosons (Goldstone's name remains a separate word). I generally see Higgs capitalized. Higgsino can go either way. --Amble (talk) 19:37, 8 August 2012 (UTC)

What about Goldstonino?--88.64.10.112 (talk) 23:02, 19 August 2012 (UTC)

Following the principle I outlined, (G|g)oldstino should start to lose its initial capital as it takes on life as a distinct word independent of the name Goldstone. In this, it's similar to Higgsino. Looking through the literature, that's what I see: it is capitalized or not rather haphazardly, about half the time each way. That's consistent with my expectation. --Amble (talk) 22:12, 2 September 2012 (UTC)

New "mathematics" section

The formulae in FT2's new section don't seem right to me. In particular, I've never seen a factor 1/Sqrt[2] in the definition of the SU(2) doublet (the first equation). As a result of that factor, the kinetic term and mass term for the complex scalar fields phi^+ and phi^0 in the second equation are not canonically normalized. Moreover, the third equation implies v ~ 246 GeV, but then the fourth equation implies e.g. m_top = (G_u)_33 v, which is incorrect (with that normalization of v, it should be m_top = (G_u)_33 v/Sqrt[2]). I think we should remove the 1/Sqrt[2] from the first equation and define the vev as <phi^0> = v/Sqrt[2]. Moreover, the statement that v "is the only parameter in the Standard Model which is not dimensionless" is clearly incorrect (mu^2 has dimension of a mass as well, and it is arguably the "true" fundamental mass parameter of the SM). Cheers, Ptrslv72 (talk) 12:33, 20 August 2012 (UTC)

Note that it says only free parameter. If you take v as a free parameter, then the Higgs mass is not a free parameter.TR 14:21, 20 August 2012 (UTC)

"free" was added after I wrote the comment above. Ptrslv72 (talk) 14:46, 20 August 2012 (UTC)

Also, the description of the "mexican-hat" potential is incorrect. The potential is plotted as a function of the real and imaginary parts of phi^0, not the real parts of phi^0 and phi^+ (obviously, a non-zero vev for phi^+ would break charge conservation). Ptrslv72 (talk) 12:37, 20 August 2012 (UTC)

As you wish, but note that the real part of phi^+ is (phi^+ + phi^+^*) = phi^+ + phi^-, which is in fact neutral. ;).TR 14:21, 20 August 2012 (UTC)

It's not "as I wish", look at the axis labels in the picture. And no, phi^+ + phi^- is not neutral, it is not even an eigenstate of the electric-charge operator Q. Ptrslv72 (talk) 14:36, 20 August 2012 (UTC)

$\phi ^{\dagger }\phi =(Re\phi ^{+})^{2}+(Im\phi ^{+})^{2}+(Re\phi ^{0})^{2}+(Im\phi ^{0})^{2}$. So, it does not matter which two you take to plot the potential.TR 14:53, 20 August 2012 (UTC)

Why do you think it doesn't matter? Check page 16 of the lecture notes I already linked below: the electric charge is conserved (and the photon remains massless) only if the vev is either all in the "up" component of the doublet or all in the "down" component of the doublet. We have chosen the hypercharge in such a way that the "up" component is charged and the "down" component is neutral. Hence, the vev must be all in the "down" component, which is why, when we plot the potential to show where the vev comes from, we set the "up" component to zero. Ptrslv72 (talk) 16:01, 20 August 2012 (UTC)

For any other vacuum state there would simply be another conserved U(1) charge which we would call Q. So, no it does not matter at all.TR 16:15, 20 August 2012 (UTC)

With the notation that you used until your latest changes (i.e. phi_up = phi^+, phi_down = phi_0 and Y=1) you were clearly implying that Q was the usual I_3 + Y/2, thus the vev had to be all in the bottom part. And in any case, the caption should be consistent with the figure, where phi_RE and phi_IM clearly refer to the real and imaginary part of one component of the doublet. Ptrslv72 (talk) 17:00, 20 August 2012 (UTC)

One more comment: in order to get the gauge boson masses given in the third equation, the second and third term in the covariant derivative (in the second equation) should each be divided by 1/2. To be more precise, this factor could still be hidden in t^a for the SU(2) gauge boson, but it definitely has to be there for the U(1) gauge boson. For a self-consistent set of formulae for the SM Higgs sector, see e.g. chapter 2 of these lecture notes. Ptrslv72 (talk) 13:19, 20 August 2012 (UTC)

And one more: since phi is a complex doublet, the kinetic term in the Lagrangian is (D^mu phi)^dagger D_mu phi, not [D_mu phi]^2 as is currently written. Ptrslv72 (talk) 13:27, 20 August 2012 (UTC)

TR, I suppose you are thinking of eq.(20.110) of Peskin-Schroeder. However, in that equation h(x) is a real field, thus the 1/Sqrt[2] is correct (so that e.g. the kinetic term in the Lagrangian reads 1/2 d^mu h d_mu h). On the other hand, in the first equation of our section phi^+ and phi^0 are complex fields, so the factor 1/Sqrt[2] must not be there (e.g., the kinetic term for a complex field is d^mu phi^* d_mu phi). Ptrslv72 (talk) 14:02, 20 August 2012 (UTC)

Yukawa couplings

TR, I see a problem in the formula for the Yukawa interactions. The Yukawa couplings are 3x3 matrices in flavor space. You can rotate the quark fields to a basis where the matrices are diagonal, but then the interaction of the charged component of the Higgs with one up-type quark and one down-type quark contains the CKM matrix. In your formula, on the other hand, the charged-Higgs interactions with quarks are flavor-diagonal. Cheers, Ptrslv72 (talk) 17:13, 20 August 2012 (UTC)

You are right (as so often). I jumped the gun on writing the whole thing diagonally. I sort of hoped to avoid mentioning the CKM matrix at all but it seems unavoidable.TR 20:38, 20 August 2012 (UTC)

Also, the charged-Higgs interactions don't look right: if phi^+ = phi_1 + i phi_2, then the second term in the first line of the Lagrangian destroys a phi^+ and an up and creates a down, while the second term in the second line destroys a phi^- and a down and creates an up. Both violate charge conservation. On the other hand, the second term of the third line is OK (it destroys a phi^+ and an electron and creates a neutrino). We should also check that the hypercharge adds up correctly in the neutral-Higgs interactions, and that the relative signs of the six terms in the lagrangiane are all correct (the latter are all fixed once we fix the signs of the mass terms and the relation between mass and Yukawa coupling). Cheers, Ptrslv72 (talk) 17:46, 20 August 2012 (UTC)

This is why I love collaborative working. Thanks TR and Ptrslv for catching these; can someone check Standard Model (mathematical formulation) to be sure any improvements here are reflected there as well? It was a direct text lift of work added by others (as noted in the edit summary); I understood its relevance to this article enough to bring it over but lack technical skills for editing and correcting gauge theory math. FT2 ^{(Talk | email)} 22:20, 20 August 2012 (UTC)

Mmmh I'm not so keen to touch the "mathematical formulation" article. As we've just seen, virtually every equation of the paragraph that you imported from there contained some inaccuracy. I suppose it's fair to expect that the rest of the article will be just as bad. Correcting it would require a lot of work, and anyway a reader interested in that level of mathematical detail should rather go for a proper scientific source (I mean, a textbook or some lecture notes). I know that you don't like this approach, but I would rather remove the link to the "mathematical formulation" article and just make sure that what we have here is fully correct. Cheers, Ptrslv72 (talk) 00:18, 21 August 2012 (UTC)

Darn, that's annoying. You're right in second guessing how I feel on that (even though disappointed to find it wasn't top notch) - we should have that article, it should be in good condition or at least error free if not perfect, and should be linked (lots of "shoulds"). The "lots of work" reason isn't too persuasive (many articles take lots of work) nor the "should use a textbook" reason (we have many technical articles in math and elsewhere, no clear reason not to cover this encyclopedic topic even if technical). Also it's nicely pitched at a good level of description. The only issue is, is it actually misinforming people to the point of "more harm than good"? I can't judge how badly a physicist would rate the "some inaccuracy". If it's capable of giving a decent idea but not 100% solid, then a tag on the page is definitely needed to warn readers, if it's all horribly wrong then chunks of the text will need deleting as well, in the worst case AFD is called for (and see if anyone can fix it). If it's not at that depth of disaster, notable encyclopedic content shouldn't be deleted unless we really can't do anything to make it useful on balance. Even leaving it linked helps to incrementally improve the wiki - this discussion is a case in point.

I suspect you might favor accuracy or nothing, but semi-accurate with tagging is often used as articles are constantly developed and may be substandard a while before someone has the impetus to fix them. Can the article in question be hat tagged in a way that adequately represents the issues, and alerts readers to the concerns? FT2 ^{(Talk | email)} 12:09, 21 August 2012 (UTC)

The "lots of work" reason is fully persuasive for what I am concerned: I have my own work to attend to on the side, and just fixing the short snippet that ended up in this article took us a full afternoon. This said, we should ask ourselves what kind of reader an article such as Standard Model (mathematical formulation) is aimed to. It is a reader who already has some knowledge of quantum field theory, otherwise all the formulae contained in the article will look meaningless to him/her. This already narrows the readership down to physics students, who usually have access to textbooks and lecture notes and should know better than looking for technical information on Wikipedia. But let's assume for the sake of the argument that the article is meant as a collection of formulae to be used as a reference by those who do understand them. Then the article makes sense only if all of the formulae are correct. Wrong signs or wrong factors of two may look trivial to the layman, but they make the formulae useless precisely to the kind of reader who might be interested in them. And again, making sure that a technical article is all correct (and that it uses a consistent notation throughout the different sections) requires a non-negligible effort which could only be provided by the minority of editors who have a working knowledge of the subject. Not to mention the fact that, once an article is cleaned up, it requires constant policing to make sure that mistakes are not reintroduced by well-meaning but non-expert editors.

To be entirely honest, I even wonder if it was a good idea to introduce the "Mathematics" section in the Higgs boson article. The readers who can understand the formulae already know all of this stuff, and they most likely have access to proper textbooks. For all the other readers the section could be off-putting, and I wonder how many of them will just stop reading there and miss the relevant (and much more accessible) information given below. Cheers, Ptrslv72 (talk) 13:14, 21 August 2012 (UTC)

I am somewhat ambivalent to having the section there. I see some virtue to having there. To readers who are able to process the mathematical notation it can be very clarifying, and I do believe there is a non-negligible subset of readers that can process this, but that does not know this already. Basically, this includes everybody that worked on a graduate degree in theoretical (not necessarily high energy) physics in past couple decades, and similarly people with degrees in high energy physics but no longer active as a physicist. With the recent media attention these people are very likely to look this article up. (Higgs physics is one of those areas that most physicists feel they should know what it is about, but only few really do.)

That being said I completely share your worry about having an off-putting while of impenetrable mathematics right in the middle of the article. It definitely is couple registers more technical than the level I was aiming for with the production and decay sections. One thing we may want to consider is having the section later in the article.TR 14:12, 21 August 2012 (UTC)

Moreover, the new section only shows how the SM gauge bosons and fermions acquire mass through the Higgs mechanism. Ironically, no mention is made of the Higgs boson itself, which after all should be the subject of the article. I wonder if this section shouldn't rather be moved to the Higgs mechanism article (which BTW is another article I'm afraid to touch lest it becomes a burden). Cheers, Ptrslv72 (talk) 13:29, 21 August 2012 (UTC)

This is also a good point. The Higgs mechanism is something a little more general than the way it is implemented in the Standard Model. It simply explains how spontaneous breaking of a gauge symmetry leads to the gauge bosons acquiring a mass through absorption of the goldstone bosons. In particular it does not necessarily include the fermion mass generation that is something very specific to the SM. Hence Higgs mechanism may not be the best home for this.

Currently, this article covers both the Higgs boson and the Higgs field. So, I think there is some room here to explain how the Higgs field interacts with the SM. If it stays here, we may need to expand with some information about where the Higgs boson itself comes into the story.TR 14:12, 21 August 2012 (UTC)

Edits since above

Good comments, thank you. It helped a lot to understand the perspectives held. Edits made:

• Math moved to end. I agree with above, also a "technical section" allows for other technical information without forking in future.
• Noticing the start of a separate Search for the Higgs boson article, I've tried to created a decent intro for it, moving over relevant material, recasting to focus mainly on the search, and then cutting down this article's length greatly, in summary style.
• The issue above - the paragraph that got moved between History and Theoretical properties because it's a bit of both - resolved I think. About 1/2 of theoretical properties was actually closer to theoretical background to why the Higgs (or something having that effect) was necessary. Before, this seemed to duplicate the "History, hopefully now it doesnt feel that way as much (but see below).

Possible "to do" -

1. Merge, with discretion, some of Introduction to the Higgs field - low quality in parts and much less need now for an "introduction" as we've written one here.
2. The "Overview" section was useful but with the forked "search" sub article and simpler (yet complete) explanation in "history" and "theoretical properties/theoretical need for the higgs", do we still need this section at all? Can we merge any useful content from it into other sections (they seem almost as easy to understand as the "Overview" anyway).
3. Add a summary of this article key points to the background section in the Search for the Higgs boson article.
4. The "History" and "Theoretical properties" section still have duplication. Is it possible the paragraphs in them are overly duplicated or could be improved by some judicious move-and-merge of their text between them? Or no need now the latter is clearly explaining a different point (by having a new subsection for that part of it)
5. Some mention (briefly) of Yang-Mills theory in the "History" section? This was where the problem of symmetry breaking and masslessness first appeared, or so it seems, years before. That article has some brief but useful history text ready to use. Can someone do this, to ensure it's correctly characterized? Also relevant for wikilink purposes: articles on Yang-Mills existence and mass gap and Yang-Mills-Higgs equations.

Any errors of precision, hopefully minor and easily fixed. FT2 ^{(Talk | email)} 05:26, 23 August 2012 (UTC)

New paragraph in the history section

I had missed the fact that FT2 moved a paragraph from "theory" to "history", I think this doesn't work. The paragraph (now the second in the "history" section) refers to the Standard Model, the W and Z bosons and the issue of fermion masses as the "source" of the problem whose solution came from the Higgs mechanism. In fact, the 1964 papers by Higgs and the others only addressed the problem of giving mass to the gauge bosons in a generic abelian model. The Standard Model was not proposed until three years later. I think that the "history" section should try to respect the chronological order of the various contributions, whereas the "theory" section we can take more liberties and present the various issues from a modern point of view. Cheers, Ptrslv72 (talk) 20:22, 20 August 2012 (UTC)

It works. I was glad to find the technical treatment in another article, and that it was at about the right level technically to use here. I noticed the probable anachronism, where the explanation why a mechanism was needed, was in terms of experimental observations and SM theories from later in the timeline.

I felt that overall the purpose of that paragraph was to explain why there was a theoretical issue, and what problem HM solved, in a bit more depth. It's not really a discussion of the theoretical properties, so much as a discussion of a historical problem with past theories and the context of the 1960s papers onward. It's unfortunate that it was cast in terms of non-sequential evidence, but overall the article significance of that paragraph seemed to be explaining a historical situation in theory development, and not describing the currently-theorized properties of the particle/field. Hence my move after inserting it, to the history section. If anyone can suggest a "fix" then go ahead, if not then Ptrslv's logic is fine. FT2 ^{(Talk | email)} 22:14, 20 August 2012 (UTC)

TR - revert?

@TR - can you reconsider this revert.

Original:

The Higgs field—if it exists—is not responsible for all mass, but only for the masses of elementary particles. For example, only about 1% of the mass of baryons (composite particles such as the proton and neutron) is due to the Higgs mechanism acting to produce the mass of quarks. The rest is due to the mass added by the kinetic energies of quarks and the energies of (massless) gluons of the strong interaction inside the baryons. Without the Higgs field, the Standard Model says that elementary fermions such as quarks and electrons would be massless.

Proposed:

The Higgs field—if it exists—is not responsible for all mass, but only for the masses of elementary fermions such as quarks and electrons, as well as the W and Z gauge bosons. Without the Higgs mechanism these particles would be massless. However only about 1% of the mass of baryons (composite particles such as the proton and neutron) is due to the Higgs mechanism giving mass to their quarks or other components. The other 99% arises due to spontaneous breaking of chiral symmetries within the strong nuclear interaction instead, in conjunction with the kinetic energies of quarks and the energies of (massless) gluons of the strong interaction inside the baryons.

Without adding length (beyond names of entities already alluded to) or "junk" info, the edit improved flow:

• The original bounced back and forth - it mentioned the Higgs field and weak force, then bounced to strong force, but then goes back to the weak force just to name the particles it affects. Illogical order, better to name these in the original mention.
• The original states 1% is due to HF and states the source of the rest - but only in terms of (arbitrary sounding) sources of energy. I see we have an article (stub but that's ok) on the exact effect it's talking about, that already states it covers "99%" of the mass of those same particles, and gives a name rather than just a list of energies. Worth linking to and giving a name.
• The note lists particles given mass by HF, but just as a list, and apparently incomplete - the note says fermions gain mass, the article says fermions and massive gauge (W/Z) bosons gain mass. Consistency matters. As HF (if proven) is responsible for the mass of any particle acquiring mass due to EWSB (almost by tautology) it's easier to say that and identify the particles as examples, which is appropriate for a note anyway. If this isn't correct it doesn't affect the other 2 points.

The original was low quality. Not fatally broken, but certainly for a brief note, fixable issues capable of better flow. FT2 ^{(Talk | email)} 21:41, 25 August 2012 (UTC)

Your edit, add a bunch of unexplained jargon for no particular good reason.

• To your first point, that is much better fixed by just leaving out the last sentence (which was just a leftover from me fixing earlier bad edits to this note).
• To your second point. Note that that article is unsourced (and so was your statement). The effect is not called "chiral symmetry breaking". In fact, saying that baryons acquire mass due to chiral symmetry breaking is rather weird. To me the opposite relation is more sensible "chiral symmetry is broken due to baryons acquiring a mass". (Also note that because of the Higgs field there is no chiral symmetry in the first place).
• To your third point. I have explained this to you already. The note said that without the Higgs field, the fermions would be massless. This correct and complete, because in the standard model without a Higgs field, the W and Z boson would still acquire a mass (albeit a much lower one) due to breaking of chiral symmetry in the strong sector. (The corresponding goldstone bosons, the pions, would get eaten be the gauge bosons to provide the longitudinal modes).

TR 11:30, 26 August 2012 (UTC)

error in box showing paths of boson formation

Below is the text in question:

Feynman diagrams showing the cleanest channels associated with the Low-Mass, ~125GeV, Higgs Candidate observed by the CMS at the LHC. The dominant production mechanism at this mass involves two gluons from each proton fusing to a Top-quark Loop, which couples strongly to the Higgs Field to produce a Higgs Boson.

Left: Diphoton Channel: Boson subsequently decays into 2 gamma ray photons by virtual interaction with a W Boson Loop or Top-quark Loop. Right: 4-Lepton "Golden Channel" Boson emits 2 Z bosons, which each decay into 2 leptons (electrons,muons). Experimental Analysis of these channels reached a significance of 5 sigma.[68][69] The analysis of additional vector boson fusion channels brought the CMS significance to 4.9 sigma.[68][69]

Note: I believe that in the last sentence the CMS significance should be changed to 5.9 be consistent with this sentence elsewhere in the article (under the heading "Discovery of New Boson"):

On July 31 2012, the ATLAS collaboration presented additional data analysis on the "observation of a new particle", including data from a third channel, which improved the significance to 5.9 sigma (1 in 588 million chance of being due to random background effects) and mass 126 ± 0.4 (stat) ± 0.4 (sys) GeV/c2,[3] and CMS improved the significance to 5 sigma and mass 125.3 ± 0.4 (stat) ± 0.5 (sys) GeV/c2.[2]

This is a very minor error in an otherwise wonderful article!!! — Preceding unsigned comment added by 50.53.129.6 (talk) 07:37, 3 September 2012 (UTC)

There's no error, the significance of the CMS result is different from the one of the ATLAS result. Cheers, Ptrslv72 (talk) 10:06, 3 September 2012 (UTC)

"Tentatively observed" in the opening sentence

User user:Bhny replaced the word "proposed" with "tentatively observed" in the opening sentence. I do not think this is an improvement:

1. The phrase "tentatively observed" is very vague without further clarification. (Which the lede does not provide until the last paragraph.
2. It confuses the context of the first paragraphs. By saying "proposed", it is immediately clear that any properties mentioned are theoretical proposed properties, not properties that have been observed.

I strongly suggest going back to just saying "proposed" which is just as factual, and a lot less awkward and confusing.TR 07:42, 7 September 2012 (UTC)

I see your point about the properties, but there are a few problems-

1. the status of the particle is "tentatively observed" not "proposed" (see infobox).
2. It's confusing for the reader who 'knows' from the popular press that it has been discovered to come here and find it is only "proposed"
3. You have to read all the way to the 4th paragraph to find out that it has been tentatively observed and not just proposed.

We could also put something like this- "...Higgs particle is a proposed (and tentatively observed) elementary particle..." which while even more clumsy is accurate. Or maybe add a short 2nd sentence that says it has been tentatively observed. Bhny (talk) 09:09, 7 September 2012 (UTC)

There is no such thing as "the" status of the particle. So your first point is rather pointless. As for the second and third points, I think we can expected enough attention span of our reader to scan four paragraphs. (The third point also works against saying "tentatively observed" since readers have to wait that long to figure out what this weasel like phrase in the openning sentence means.

An alternative could just be omitting an adjective altogehter and just say. "The Higgs boson is an elementary particle in the Standard Model of particle physics." This is completely accurate , establishes the right context, and is considerably less awkward.TR 10:21, 7 September 2012 (UTC)

I support removing the adjective from the first sentence. If we do that, the last sentence of the first paragraph should certainly mention that a particle consistent with the Higgs boson has been detected at CERN. --Amble (talk) 14:58, 7 September 2012 (UTC)

I'm fine with what Amble and Timothy say- omit both and add a sentence at the end of the first paragraph saying "A particle consistent with the Higgs...." Bhny (talk) 17:11, 7 September 2012 (UTC)

We might also rework the first part of the second sentence to say that the Higgs was included in the standard model for theoretical reasons, and that it may now have been detected experimentally. The current "The Higgs boson's existence would have profound importance in particle physics" is not as informative as it could be. --Amble (talk) 17:42, 7 September 2012 (UTC)

This all sounds good. Do you want to do the edit? Bhny (talk) 18:41, 7 September 2012 (UTC)

I've made an attempt -- edit away. --Amble (talk) 23:18, 7 September 2012 (UTC)

Thanks, looks goodBhny (talk) 03:35, 8 September 2012 (UTC)