Talk:Standard Model/Archive 1

Leading Paragraph[edit]

Half of the leading paragraph (one long sentence) is about how the Standard Model is not a theory of everything. This sentence seems unnecessary since neither the blurb above it nor the rest of the article makes it explicit that it is approximately a TOE. Neither the general public nor the researchers in high energy physics mistake the standard model to be one. I feel that this sentence needs to be moved to a separate section elsewhere in the body of the article (preferably at the end), where extensions beyond SM and theories including gravity may be discussed. --TriTertButoxy (talk) 00:59, 25 March 2008 (UTC)[reply]

Review request and other remarks[edit]

There is a table listing the respective values for measured and predicted values of particle masses, for the W boson 80.398±0.025 and 80.3900±0.0180, for the Z boson 91.1876±0.0021 and 91.1874±0.0021.

I've never seen a calculation predicting these values. Rather it is known that the standard model describes masses as free parameters. Can anybody help me ?

—Preceding unsigned comment added by 89.60.187.242 (talk) 09:59, 20 January 2008 (UTC)[reply]

Add a section on history of the standard model's discovery, including links/citations to original papers. C9 (talk) 04:25, 7 January 2008 (UTC)[reply]

Could someone please review the noncommutative standard model page and either merge the relevant content, or propose deletion of that page? I don't know enough about the particle physics community to know if that material is noteworthy. Vessels42 18:16, 14 December 2006 (UTC)[reply]

Shouldn't the elementary particles also be mentioned, in addition to the forces? I.e. two quarks, electron and neutrino, and then two more families like that. AxelBoldt

Talk:Standard Model/Sandbox - formatting experiment

Shouldn't we mention the Minimal Supersymmetric Standard Model?

Go to http://www-wisconsin.cern.ch/physics/files/r20401.pdf. It has proof that Higgs particles have been found.

Perhaps it would be helpful to include a cross reference to the photino in the See Also section?

Be bold! If you think it belongs there, add it! moink 07:42, 7 Mar 2004 (UTC)

(p.s. yep. it appears i'm following you around:) )

Confusingly, this new model is still called by the same name as the old one: the Standard Model.

Removed this sentence. The Standard Model is a working model, not a fundamental theory. As such it is constantly refactored to account for new data and new ideas. The Standard Model is the state-of-the-art in physics—the model is expected to evolve.
—Herbee 11:27, 17 Sep 2004 (UTC)

User:Agasides added the "varying physical constants" material back to the article, saying Its not a speculation. Go find a laboratory similar to Webbs laboratory, and repeat the experiment.. Unfortunately, it is a speculation, very much outside of the mainstream of physics. That doesn't mean it's wrong, just that it hasn't met the burden of proof necessary to convince the rest of the physics community of such a radical phenomenon. Unconfirmed speculations belong on arXiv.org, not Wikipedia. Anyway, as [1] makes clear, the present experimental data implies that even if the value of constants like α are actually position-dependent, the variation is unbelievably tiny; it's hardly a repeatable lab experiment. -- CYD

Accessibility[edit]

Is the best way to add material for particle physics novices to simply expand this article, or to add a companion article, a la Special relativity for beginners? -- Beland 00:54, 16 August 2005 (UTC)[reply]

Obviously this article gets too technical too fast for a general encyclopedia, but most of the physics articles I've seen in Wikipedia have the same kinds of problems. There is a lot of good information but it isn't put together in a very insightful way. The problems with the Dirac Equation article are tons worse than this "Standard Model", which at least gets to the point. The Dirac equation looks like someone is trying to write a physics textbook. Maybe Wikibooks would be a good place for that stuff? Non-specialists probably want to know what the standard model is and why it's important rather than immediately get lots of links to fermions and bosons etc. Some person who wandered in to this article hoping to find out something about "standard model" would be a little disappointed or bewildered. I'm not too sure what to do about it though.--DannyWilde 01:25, August 16, 2005 (UTC)

I'd like to see a "history of the standard model" section, although that'd be pretty close to "history of particle physics". - mako 02:02, 16 August 2005 (UTC)[reply]

I'll try to add in a significant amount of detail, mostly at a pedestrial level. There is a lot of interesting facts about the Standard Model that elude even the authors of most advanced texts on this topic, and numerous other details that are rarely mentioned in any book on quantum field theory, much less in popularized accounts of the theory.

The Standard Model is wrong about neutrinos[edit]

The Standard Model says neutrinos are mass-less and therefore move at the speed of light but neutrinos do have mass, because they do change over time(a particle moving at the speed of light can not change because it's clock has stopped). This was proved by experiment after the number of expected neutrinos from the Sun and in the atmosphere did not appear in the detectors used.

NOVA just released a program on this. "In this program, NOVA probes the secret ingredient of the cosmos: swarms of invisible particles that fill every cubic inch of space and just may explain how the universe was created. Trillions of ghostly neutrinos move through our bodies every second without us noticing a thing. Yet without them the sun wouldn't shine and the elements that make up our world wouldn't exist. This program explores the 70-year struggle so far to understand the most elusive of all elementary particles, the neutrino.

Narrated by British actor Juliet Stevenson, "The Ghost Particle" is the story of a discovery that altered scientists' understanding of what the universe is made of and how it was first formed. NOVA accompanies scientists into the laboratory, revealing astonishing footage of bizarre experiments. Computer animation brings to life the neutrino particle, which is at once invisible and yet utterly essential to all life.

The program first takes audiences back to 1930, when Austrian physicist Wolfgang Pauli wrote to his colleagues about the phenomenon of radioactive decay. The experts were puzzled by a missing bit of energy that could not be accounted for in their picture of how a radioactive atomic nucleus decays. Pauli suggested that an exquisitely tiny, previously unknown particle had to exist to account for the missing energy. The problem with this theory, however, was that there was no hard evidence of neutrinos' existence.

It seemed to be an impossible investigation. Neutrinos have no electric charge, making them invisible to ordinary detecting equipment. Truly poltergeists among particles, they can pass directly through thousands of miles of solid matter without slowing down. Yet every element vital to life, including carbon and oxygen, is made by a chain of nuclear reactions that would be impossible without neutrinos. They are an essential ingredient of the universe, and catching these neutrinos became the ultimate scientific quest (see Case of the Missing Particles).

NOVA sits down with Professor John Bahcall and Nobel Prize winner Ray Davis, two men determined to solve one of the biggest puzzles in particle physics. In the 1960s, they began their scientific adventure with a daring underground experiment that few believed could succeed. Vindication for both men is a long time in coming ... but come it does." The transcript will be avaible soon at http://www.pbs.org/wgbh/nova/transcripts/3306_neutrino.html.Timothy Clemans 18:51, 22 February 2006 (UTC)[reply]

There are a couple of mechanisms by which to add neutrino masses to the Standard Model, and although they are not official parts of the Standard Model, they are certainly consistent with it. Thus to say that the Standard Model is wrong about neutrino masses is overstating the case a bit; neutrino masses can be accomodated without changing anything else. As I understand it, the main reason one of these mechanisms hasn't been added officially to the Standard Model is that physicists don't know which one is correct yet. -- SCZenz 19:13, 22 February 2006 (UTC)[reply]

I would only say a standard Dirac-style neutrino is really consistent with the Standard Model. A Majorana-style neutrino would definitely be new and weird and beyond-the-SM. Thankfully, there's no evidence for that. -- Xerxes 20:35, 22 February 2006 (UTC)[reply]

The Standard Model, as far as I can tell, is just a humungous ad hoc Lagrangian that happens to explain everything we've ever seen in particle physics—how, then, is one type of new term consistent and the other weird and different? (I ask this out of ignorance, rather than disagreement.) -- SCZenz 22:25, 22 February 2006 (UTC)[reply]

Actually, it's neither humongous nor ad hoc, but is merely presented that way in most treatments. It can be written in one line, with the right representation (and factoring) of the fermion space; the latter, in turn, exposing the high degree of regularity of both the fermion and boson spectra and regularities in the Standard Model, itself, that receive little or no airplay. The Lagrangian is written out in full here (http://federation.g3z.com/Physics/index.htm#StandardModel) with graphic depictions of the regular structure of the fermion and boson spectra that are quite striking. -- Mark, 5 April 2007

===I cant understand how something that gets rid of the difference between a constant and a variable can be other than a variable. And since it moves with the speed of light and has no mass, what can it have that's not a variable? WFPMWFPM (talk) 00:42, 11 October 2008 (UTC) ===We can have variable amounts of "bundles" of light energy; but that's what light is, and it can be stopped by a sheet of paper. WFPMWFPM (talk) 06:58, 11 October 2008 (UTC)[reply]

Symbols in the Table section[edit]

What was wrong with my edit? The symbols I used may have a slightly different meaning, but they are completely standard. Insisting on the charge conjugation symbol would be too pedantic even for a field theory classroom, which Wikipedia is not. Furthermore, my edit was consistent with the notation at List of particles, Neutrino, Meson, and who know hows many other Wikipedia articles.

Given all that, I'll revert back to myself. Melchoir 21:53, 23 February 2006 (UTC)[reply]

It's not pedantry, it's just correctness. The field/field-bar symbols imply that we're talking about full Dirac spinors, which we clearly are not, given that the columns are headed according to field chirality. I agree that field/field-bar symbols are prettier, if you want to use that notation, the rest of the table needs to be changed so that the whole remains correct. -- Xerxes 22:21, 23 February 2006 (UTC)[reply]

I don't think we should interpret the symbols as Dirac fields anyway; they're just names. Using an overbar on the name of a particle is not the same as Dirac adjointing a Dirac spinor; I don't know what would happen if you complex transposed the letter "u" and multiplied by \gamma^0. It's unfortunate that these meanings have the same notation, but there you are.

As for field chirality, I'm not sure why the table needs to say "left-handed" at all. In a (low-energy) experiment or calculation, you have to deal with the full Dirac electron/up/down anyway; the neutrino is still up in the air, but I don't personally understand those. Melchoir 22:40, 23 February 2006 (UTC)[reply]

As far as I know, q-bar (with q being whichever letter) is the standard symbol for an antiquark among experimentalists, or anyone else who isn't doing something with extreme rigor. Am I missing something? -- SCZenz 22:53, 23 February 2006 (UTC)[reply]

I see what the problem is now. Why the hell are the columns headed by field chirality? Who on earth is this for? -- SCZenz 22:53, 23 February 2006 (UTC)[reply]

It's a very standard way of enumerating the degrees of freedom of the Standard Model. This way, you can see the representation structure of the theory. It's helpful for working out anomalies and that sort of thing; personally, I feel that this kind of table encodes much of the beauty of the structure of the SM. Anyway, the point being that the table does not list realistic particles; specifically it does not assume mixing of chiralities. The notation has to reflect that or the table has to change. -- Xerxes 23:22, 23 February 2006 (UTC)[reply]

If the table is primarily meant to exhibit the representations, that makes sense to me; it's a purpose not served elsewhere. Why don't we:

Rename the table: "Fermionic degrees of freedom" or somesuch
Preface the table with a prominent link to List of particles
Delete the "mass" column entirely
Use whatever symbols you like

I think the table should also be a bit smaller, but that's less important. Melchoir 00:18, 24 February 2006 (UTC)[reply]

Good ideas! I think we should also add a table of "free parameters of the Standard Model", which is where those masses (Yukawa couplings) actually belong. I'll work on that later today. -- Xerxes 16:10, 24 February 2006 (UTC)[reply]

Actually, when the masses are removed from the table, we can collapse all three generations into eight rows. Melchoir 21:16, 24 February 2006 (UTC)[reply]

I should know these things cold, but at risk of flaunting my ignorance, the hypercharge line on the table looks to me like it's calculating the quantity which, while often known as hypercharge, corresponds to the Wikipedia article weak hypercharge (and, then it seems to be divided by 2 with respect to the definition there). Also the link on the word hypercharge seems to go to the hypercharge page, and not to the weak hypercharge page. Or maybe I'm wrong?JarahE 17:51, 27 April 2006 (UTC)[reply]

Looks like you're right to me, tho I'm unsure which factor of 2 is more conventional. -- Xerxes 18:31, 27 April 2006 (UTC)[reply]

You are correct that the "Hypercharge" is actually half of the Wikipedia article's Weak hypercharge. I have made the requisite changes. (I know there are some that insist that the "modern" usage is to simply call it "hypercharge", but, especially since "hypercharge" was being auto linked to [strong] hypercharge, it most certainly wasn't helpful. In addition, the factor of two error, that's been there ever since 8 August, 2003, made it very difficult to determine what was actually meant to be there.) -- DWHalliday (talk) 20:38, 23 March 2008 (UTC)[reply]

References[edit]

Is Deep Down Things really a reference used to verify this material, or is that an ad I see? Melchoir 04:19, 29 April 2006 (UTC)[reply]

Illustration[edit]

Could someone come up with a better illustration than the existing wall-poster? Much of the text is impossible to read, even at high resolution, and in my view the image adds little or nothing to the article at normal size.--MichaelMaggs 19:08, 14 August 2006 (UTC)[reply]

problem with the tables ?[edit]

Hi,it seems to me there are some problems with the tables

particles and anti-particles should have opposite additive quantum number but there it seems no antiparticle forms a doublet under the weak interaction! The positron and the electric anti-neutrino should transform into each other under $SU(2)_{weak}$ and have non vanishing weak isospin numbers, no ??
hypercharge is a concept defined for hadrons but the table gives non vanishing hypercharges for letpons as well ? Isn't there a confusion between hypercharge and weak hypercharge here (hadrons having both of them) ? I think it would be better to display weak hypercharge rather than hypercharge.

As I presume these tables must have been crossed checked a certain number ot times I prefer to ask and get comments before changing anything to it. LeYaYa 13:19, 7 October 2006 (UTC)[reply]

I agree the table needs some major revising. And by the time the LHC gets booted up standard model might turn out to be completely wrong.-MJH 20:24, 8 October 2006 (UTC)[reply]

completely is too much a statement as one cannot undo the previous successful experiments which confirmed many aspects of the SM (unless you doubt the conclusions of the experiments at the same time but that's starting to be a lot of mistakes :) ). The only remaining piece is the Higgs boson but it has already started to show up at the end of LEP even though not enough to give conclusive results. Nevertheless, even if one can argue that SM is incomplete it would be highly difficult to prove it wrong and be consistent with current observations. regards, LeYaYa 19:48, 10 October 2006 (UTC)[reply]

LeYaYa, if you look at the top of the table, you will see that this is a table for the left-handed fermions of the standard model. most books do not include a table for the right-handed particles because these can easily be obtained from the left-handed table since, as you pointed out, there is a symmetry between the quantum numbers. Left(right)-handed particles and right(left)-handed anti-particles have oposite quantum numbers.

To answer your other point, what was once called a weak hypercharge is simply called hypercharge in modern days, and what used to be simply called hypercharge must be qualified somehow (either as flavor hypercharge, or in some other way). The reason for that is the fact that weak hypercharge is a gauged symmetry of the standard model, and therefore much more proeminent then the flavor hyprcharge which is an accidental symmetry due to the fact that the quarks u,d,s all have relatively small masses. Dauto 02:26, 13 May 2007 (UTC).[reply]

You may well be correct that among certain circles the "modern" usage is to simply use "hypercharge" when referring to weak hypercharge. The problem, here is twofold: 1) The "Hypecharge" header auto linked to (strong) hypercharge, rather than what you claim; and 2) the values are half of what the correct weak hypercharge values should be. What bafles me is how this has remained uncorrected since its introduction on 8 August, 2003! (I have made the requisite changes.) -- DWHalliday (talk) 20:47, 23 March 2008 (UTC)[reply]

The main table is not good. It's way too long, I find the use of both weak charge and weak isospin confusing. The neutrino information implies that the neutrinos are Dirac rather than Majorana (which is the current opinion) and there certainly isn't a limit of 2 eV on their masses. I will delete the right handed neutrinos, but I think that this table isn't necessarily up to snuff on several different fronts. jay 17:21, 13 May 2007 (UTC)[reply]

Having both weak isospin and weak charge is confusing, so I removed the weak charge. I also changed the masses to 3 sig figs (where it is known) since errors aren't being quoted. I changed the names of the antiparticles in order to reduce the possible confusion of ( bar(t) )^* = t. jay 19:06, 15 May 2007 (UTC)[reply]

Having both the weak isospin and the representation dimensions is redundant, that`s true. (beats me why some people like calling these dimensions "charge" ). But it is important to let the readers know at a glance which particles are grouped together in a given representation under the weak SU(2) transformations. As it is, these tables are failing to do that. Any sugestions?

Defense of Table The table is actually cited by others as the best part of the page! James Stein, of California State University, in his book 'How Math Explains the World' (HarperCollins, 2008), says "[Wikipedia has] an excellent short exposition of the Standard Model, along with a beautiful chart that puts the periodic table to shame. You have to click several times on the chart before you get to a readable resolution, but it's worth it" (p.40).24.63.20.31 (talk) 15:52, 10 May 2008 (UTC)Michael Ringel[reply]

for the lay reader[edit]

Here's a 2003 critique of the Standard Model and another one. Billbrock 09:32, 30 October 2006 (UTC)[reply]

Critique is the wrong word here. Everyone agrees it's a great theory which makes astoundingly accurate predictions, and everyone also agrees that it has some technical holes that ought to be patched up by a new theory with new particles or other observables. Gordy Kane is an advocate of some particular ways of patching those holes, and what he has to say will be interesting. -- SCZenz 17:37, 30 October 2006 (UTC)[reply]

"Critique" may not be the ideal word, but it's OK; cf. Moby-Dick. Billbrock 19:35, 30 October 2006 (UTC)[reply]

Tests and predictions[edit]

This section is pretty bad currently. The W boson had been discovered before the standard model, I believe. And the existence of the charmed and top quarks is not really a prediction of the standard model as such. The prediction of the Z, with the correct mass relative to the W, was an extraordinary achievement, and should be emphasised. Some of the successes of QCD also need to be included. Shambolic Entity 02:12, 5 November 2006 (UTC)[reply]

Challenges to the Standard Model.[edit]

I think the main Challenge to the Standard Model is to find the Higgs particle. Since it has not been found, the status of the model or better the theory is unconfirmed. Not mentioning this as the main challenge on the page is misleading. Aoosten 22:16, 9 June 2007 (UTC)[reply]

Isn't a neutrino with a mass a greater problem? That is: the solar-neutrino problem, that has now been solved by assuming the neutrino having a mass... Said: Rursus ☻ 07:17, 5 February 2008 (UTC)[reply]

Revamping of Article[edit]

As you can see, I've recently begun a personal project of rewritting and reorganizing this article. So far, I've rewritten the first third. I hope the new version is easier to follow for nontechnical readers -- please check this.

Now, In the middle of the article there's a series of three huge tables of fermions which I find exceedingly unaesthetic. I've decided to create 'summary' tables of particles within each subsection, which I think is easier to follow.

Since this is an encyclopedia, I am completely for the idea of having a detailed "master" table of all particles (which the three giant tables seem to strive to be). But, can somebody (who's adept at making tables) make a nicer looking one that we could put at the end of the article so that it doesn't look so intimidating and put off any potential readers who might be curious about the state-of-the art theory of physics? —The preceding unsigned comment was added by TriTertButoxy (talk • contribs) 06:02, 6 January 2007 (UTC).[reply]

I left a note on your talk page: great work on the article... but if you're going to rewrite the whole thing, could you cite your sources as you do it? It's important for verifiability. Thanks. -- Rmrfstar 18:19, 6 January 2007 (UTC)[reply]

All of the material I've written is 'common' knowledge among particle physicist, and so, my citations would come from one (text)book. How do you propose I should do the inline citations from the book? Or would you prefer if I got lots of different texts on particle physics? TriTertButoxy 18:03, 15 January 2007 (UTC)[reply]

Wikipedia:Scientific citation guidelines#Uncontroversial knowledge should help you. As it says, "Therefore, in sections or articles that present well-known and uncontroversial information ... it is acceptable to give an inline citation for one or two authoritative sources at the start". This is followed by a good example of how this is best-done. -- Rmrfstar 18:13, 15 January 2007 (UTC)[reply]

Just as a minor note...there are no explanations for the terms "SU(3), SU(2), and U(1)" and all that in the article. -Running On Brains 05:11, 26 February 2007 (UTC)[reply]

I've made another giant edit. This time the TOC outlines the material that needs to be added.--TriTertButoxy (talk) 06:20, 2 March 2008 (UTC)[reply]

Major rewrite? The article is much worse[edit]

It seems to me that the changes made by User:TriTertButoxy could stand some review. The articleis now without the CPEPweb diagram, the "Force-mediating particles" diagram and the list of fermions and their properties. There are now many empty sections in the article. All you have done is add a messy outline or a "todo" list into the article text. I do not think that anybody else wants this article to simply be a long wish-list of "other SM-related articles and sections that we would like to see". It might be that we need a History of the Standard Model article, but that is separate. There must be a place in the Physics WikiProject for a "todo" list like this.

Even the lead paragraph that TriTertButoxy put in was highly self-referential and almost apologetic about what the intend of this article was. I removed that, but then stopped. If you intend to herd our editors in a particular direction, then do so on this talk page. In the future, when making such edits on a copy in your userspace, please at least use the {{Inuse}} template.

This represents a serious degradation in the quality of the article. I think that TriTertButoxy should demonstrate in writing that why he did what he did serves any purpose to improve the article quality by stating his goals in the changes he made. I am going to wait a few days for input from others, but I am inclined to revert this rewrite and then come up with set of goals for what we want the article to be.--Truthnlove (talk) 07:45, 2 March 2008 (UTC)[reply]

I vote for a revert. --Michael C. Price ^talk 01:54, 5 March 2008 (UTC)[reply]

I decided to re-implement the information I thought was important over at Elementary particle and Fundamental interaction. I will rarely return here. Maybe that is how the information should be organized.--Truthnlove (talk) 07:11, 3 March 2008 (UTC)[reply]

Sorry; I honestly thought I was being bold. This was my second major rewrite of the article -- and despite the sucess of my first rewrite, it looks like I went a little overboard this time. I really didn't mean to ruin the article. I also didn't mean to make the introduction sound apologetic. I think the statement "presently, it represents the summary of vast data collected by thousands of natural scientists across several disciplines since the beginning of modern science, culminating in the electroweak unification and on the discovery of asymptotic freedom in quantum chromodynamics" made it sound that way. Though, I'd like to make it clear that the standard model is a theory of such scope. The diagram I removed summarized the interactions between the particles, and was in fact created by me. After some thought, I felt that it was quite misleading, since it suggested that gluons and photons can't interact with the higgs boson. They actually can (dynamics are governed by the quantum action not the classical one). As for the table listing the quantum numbers and masses of all the particles, I intend to create another table in the future that doesn't look so overwhelming. I got rid of the passage regarding the anthropic principle because the standard model isn't a theory of everything, whose parameters need any explaining. Oh well... Truthnlove, your comments on my talk page were rather harsh, and I would have much preferred an immediate reversion of the article instead of such negative critisism. Though I do see my mistake. —Preceding unsigned comment added by TriTertButoxy (talk • contribs) 03:45, 4 March 2008 (UTC)[reply]

If the deleted material on a number of topics (including diagrams) is not restored I suggested reverting the article. Being told that it may reappear in the future is not good enough. --Michael C. Price ^talk 01:52, 5 March 2008 (UTC)[reply]

I have restored the lost particle diagrams etc. Please do not start future "rewrites" with massive deletions without finishing the job properly.--Michael C. Price ^talk 13:46, 8 March 2008 (UTC)[reply]

Weak Interactions[edit]

The figure in subsection Force Mediating Particles doesn't show up a $W^{+}W^{-}Z$ -coupling, but SM provides such a vertex. May anyone change the graphic by adding the missing line? --CHamul 09:02, 16 January 2007 (UTC)[reply]

Thanks! It's fixed now. TriTertButoxy 00:10, 17 January 2007 (UTC)[reply]

Isn't ZZ coupling predicted by SM as well? —Preceding unsigned comment added by 142.90.114.45 (talk) 23:21, 31 July 2008 (UTC)[reply]

Yes it is, and a line should be there. BUT, the graph is becoming increasingly tangled and difficult to understand with each edge that needs to be drawn between the gauge bosons. When I originally created it, I intended for it to give a rough overview of the interactions among the various particles in the standard model. I've come to realize that all it does is to indicate which interactions occur merely at "tree" level. Labeling an interaction as "tree" level is purely artificial, and simply reflects the perturbative method used to extract physical results. While most "tree" level interactions indeed capture the essence of standard model dynamics, it misses some other important physics such as the decay of the higgs boson to two photons. Of course, such a process is mediated by a fermion loop. But does that warrant an omission of such a line in the graph that was supposed to give an overview of interactions? Absolutely not.

Perhaps, I (or we) could abandon the original purpose of the graph, in favor a new one -- to illustrate the interactions that occur in the standard model at tree level (this is what it currently seems to be doing). Since there is a near one-to-one correspondence between the terms in the Lagrangian, and the vertices appearing in Feynman diagrams, the graph would only illustrate the terms appearing the standard model Lagrangian. Maybe, this could be useful to the physics in the field studying the standard model. But this is quite useless to the general reader. Furthermore, nature does NOT evolve in time perturbatively. I believe the graph doesn't serve its purpose, misses important physics, and is overwhelming. I am going to remove this graphic from the article. Are there are objections? --TriTertButoxy (talk) 17:58, 7 August 2008 (UTC)[reply]

Challenges to the Standard Model[edit]

This ridiculous statement appears "Alain Connes has shown that the standard model can be derived from general relativity by generalizing Riemannian geometry to noncommutative geometry." That would be amazing! Would someone please fix it to read properly? I don't know what was intended. If I see it there next time I check, I'll delete it. 06:43, 26 March 2007 (EST)

You can check, for example, hep-th/0111236 131.111.8.96 20:13, 29 March 2007 (UTC)[reply]

I wrote the statement that you qualify ridiculous. The statement is not mathematics and I do not pretend to be able to prove it. Neither is Einstein's derivation of general relativity provable. However both theories, Einstein's and Connes' are confronted with experimental numbers. I thought that this is what physics is about. If you have a different criterium, please tell me and I may try to satisfy you before you check next time and delete me. Schucker 22:51, 1 May 2007 (UTC)[reply]

I have read hep-th/0111236 and this article is not very pedagogical or conclusive -- in particular it does not definitively support the claim given in the wikipedia article. I know that the statement in the wikipedia article is not the consensus view of physicists and do not believe that such speculative statements should be listed in the Standard Model article. jay 18:30, 4 May 2007 (UTC)[reply]

I agree on; reference to Alain Connes and that standard model is derivable from general relativity should be removed, as this claim is totally out of mainstram physics. IlkkaP 21:29, 28 May 2007 (UTC)[reply]

Gauge group???[edit]

How come there can be an article on the Standard Model and not mention the gauge group ${\rm {SU(3)\times SU(2)\times U(1)}}$ ??? 131.111.8.96 20:15, 29 March 2007 (UTC)[reply]

Accessibility[edit]

I've had a go at reworking the overview "Standard Model" section of this article lightly, with the aim of maiking it more accessible to non-physicists, without "dumbing down" the good quality of detail.

We could do better, make the statement more accessible to people in general. Hopefully the edits are good ones. I've tried to tweak the main "Standard Model" section to introduce the components and their roles, and put the Standard Model in a context, so readers can learn easier, rather than just describe their spin etc for physicists alone. Hopefully its a Good Thing.

Main edit areas:

"Overview" paragraph at the start of the "Standard Model" section, to contextualize better.
Language use: eg,
- Old: "For pedagogical purposes, the description of the Standard Model is divided into three parts",
- New: "For ease of description, the Standard Model can be divided into three parts."
Clarification that "odd" names like "spin", "charm" and "flavor" are names for properties of particles (obvious in physics, not obvious to newcomers seeking a basic overview or understanding of what the Standard Model is)
Clarification what a "force mediating particle" is - how the standard model interprets forces as being due to the exchange of particles. Essential background knowledge needed to make any sense of the term "force mediating particle".
Higgs Boson - was not described at all, save in terms of spin, hopes of discovery and that it plays a "unique" (but not described) role. Brought the barest basics over from that article to fill the gap.

DIFF.

Please check edit for anything inadvertantly dumb! :)

FT2 ^{(Talk | email)} 14:01, 1 July 2007 (UTC)[reply]

Could someone expand on the concepts of "left-handed" and "right-handed"?[edit]

The terms "left-handed" and "right-handed" appear with no definition in the discussion of the gauge-bosons. Could someone explain this concept, or perhps just link to the entry on Chirality (physics)?

W.F.Galway 00:19, 2 July 2007 (UTC)[reply]

Left handed means that, in the limit as the particle approaches c (or mass goes to zero), the spin and momentum are anti-parallel (helicity = -1). For right handed particles helicity = 1.--Michael C. Price ^talk 21:45, 16 February 2008 (UTC)[reply]

Color Charge in the Table[edit]

The color charge of each of these fields is fully specified by the representations. Quarks and antiquarks have color charge 4/3, whereas gluons have color charge 8. All other particles have zero color charge.

--Wikipedia article on color charge

These designations do not match what is listed in the table, despite the table's column header directing the reader to visit the color charge article. Some clarification is in order, as clearly the 1s and 3s currently in the table are designed to represent the particle belonging to the color singlet, or color triplet representations. However, as it stands I can easily see this being a possible source of confusion among non-physicists, who upon seeing that the electron has a color charge of "1" conclude that it does partake of strong force interactions, though with one-third the strength that quarks do. -- Balcerzak 03:02, 10 July 2007 (UTC)[reply]

More history[edit]

I believe the names Glashow, Salam, and Weinberg should appear somewhere in this article, since they received the 1979 Nobel prize for developing this theory. 194.94.224.254 15:54, 11 August 2007 (UTC)[reply]

Unifying the Standard Model with Gravity[edit]

Hey, I read this on Slashdot and thought you guys might enjoy. I didn't see it in the talk page and I certainly don't feel comfortable editing the main page with the information. Source:

http://www.telegraph.co.uk/core/Content/displayPrintable.jhtml?xml=/earth/2007/11/14/scisurf114.xml&site=30&page=0

Djdoobwah 02:05, 16 November 2007 (UTC)[reply]

For a few dollars more...[edit]

Hi

Can anyone give some more explaination in the caption to "Log plot of masses in the Standard Model". For instance what is the Y axis (Im assuming that there is one as things are spread out on it), and what are the boxes for (mass group maybe?).

Thanks

John

CaptinJohn (talk) 14:43, 22 November 2007 (UTC)[reply]

I'm only guessing here, but: x-axis is the mass, where the green boxes are used to indicate certain mass ranges (and hence the whole pic should not be considered four different plots as I initially did). X-Ranges (on black boxes) probably indicate the (un-)certainty to which the masses are known. The y-dimension seems to be simply used for a bit of grouping (meaning the y-extent of an entry has no meaning): Starting from 1st row with charged leptons (muon not labeled, neutrinos naturally not displayable on a log-plot), vectorbosons (again, photon missing due to m=0) with some miraculous four bars for W and Z, up-type quarks, down-type quarks and finally some bound states and the Higgs-vev in the last row. And considering that's just my interpretation and that I know the SM, I'd argue that the plot should be removed (or at least significantly improved, at the very least by labeling the axes)- no one not knowing the SM beforehand will even remotely understand it. --78.50.224.186 (talk) 02:52, 17 December 2007 (UTC)[reply]

Table of particle interactions[edit]

On picture Elementary particle interactions.svg, shouldn't be the W-boson interacting with itself? Thank you. --Irigi (talk) 14:57, 11 February 2008 (UTC)[reply]

Yes it should. All the electroweak bosons (A, Z, W+, W-) interact with each other; the W's also self-interact since they carry charge and isospin.--Michael C. Price ^talk 11:25, 14 February 2008 (UTC)[reply]

It is OK now, Stannered fixed it. Thank you for advice! --Irigi (talk) 08:33, 25 February 2008 (UTC)[reply]

Navigation template[edit]

I changed {{Quantum mechanics}} to {{Quantum field theory}}. Sorry about the earlier iterations.--Truthnlove (talk) 04:57, 2 March 2008 (UTC)[reply]

Intro[edit]

I don't know if the general public will understand "It unifies the electroweak theory and quantum chromodynamics into a structure denoted by the gauge groups SU(3)SU(2)U(1)." and so I believe it should be differed to somewhere in the middle of the article where the terminology can be explained.

I do think that it is important for the audience to understand that the Standard Model represents a compendium of scientific data since the beginning of modern science, which I believe should be stated somewhere in the introduction. --TriTertButoxy (talk) 06:21, 3 March 2008 (UTC)[reply]

===Mass values=== If an Up Quark has 3 Mev and a Down Quark has 6 Mev (Mass values), Then a Proton, with 2 Ups + 1 Down would have 12 Mev. And a Nuetron, with 1 Up and 2 Downs would have 15 Mev. Is that Correct? WFPMWFPM (talk) 17:22, 11 October 2008 (UTC)[reply]

No, it is not correct. there is more to the mass of a composite particle like the proton then the sum of the masses of the valence quarks it is built out of. —Preceding unsigned comment added by Dauto (talk • contribs) 04:29, 29 December 2008 (UTC)[reply]

I have removed the sentence about gravity being SO(3,1) since it is very misleading. Adding gravity to the standard model is not a matter of adding SO(3,1) to the gauge group, indeed gravity is not even a gauge theory (in the sense that a mathematician would use the words). Edsegal (talk) 18:26, 16 March 2010 (UTC)[reply]

SO(3,1) was misleading since that is the Lorentz group of special relativity, but gravity is a gauge theory. --Michael C. Price ^talk 18:43, 16 March 2010 (UTC)[reply]

Positrons not opposites of electrons?[edit]

The table lists values for weak isospin and (weak) hypercharge of the positron that are not the opposite of those for the electron. Could someone explain this? I've heard countless times that the positron was simply the opposite of an electron, or at the least, equivalent to an electron reversed in time. Yet this hints at some major difference between them. I think at least a sentence explaining this difference and what it means is in order here. The article positron is very short and does not detail any of these properties or what they mean and could also use much work. Wnt (talk) 22:32, 20 July 2008 (UTC)[reply]

The reason is that when people say "electron" and "positron", they are not talking about the ordinary electron and positron, but helicity eigenstates in a world where the mass of the electron is zero. These are the only quantities with a well defined notion of weak isospin and weak hypercharge. Once the Higgs mechanism occurs, the weak isospin and weak hypercharge look broken, and the mass eigenstates don't have definite values for these.Likebox (talk) 20:35, 3 November 2008 (UTC)[reply]

More to the point of the question, the table shows only the eigenvalues for the lefthanded particles (by convention). The righthanded positrion will indeed have the opposite eigenvalues of the lefthanded electron as expected. Dauto (talk) 04:23, 29 December 2008 (UTC)[reply]

Standard model `incompatible with neutrino oscillations'?[edit]

Sure "incompatible" means: "no way the standard model can describe neutrino oscillations". This is certainly wrong -- neutrino oscillations only require a small re-parametrisation of the model. So, unless somebody comes with an explanation, I guess I will have to change the sentence to "the discovery of neutrino oscillations will result in certain changes of neutrino related parameters of the standard model". Is that OK? (Bakken (talk) 21:54, 3 November 2008 (UTC))[reply]

Neutrino masses require an extra non-renormalizable interaction with the Higgs field. This is the term LHHL in the schematic notation of the fields section, and this is not part of the standard model because it is not renormalizable.

The "extra parametrization" is by introducing phenomenological neutrino masses and mixings, but the renormalizable standard model is unequivocal--- the neutrino masses are zero. A GUT with a right-handed neutrino can generate neutrino masses, but that's the same as introducing a non-renormalizable interaction in the effective theory.Likebox (talk) 22:22, 3 November 2008 (UTC)[reply]

I think I might be unclear above--- let me say it like this: for all choices of parameters in the standard model, the neutrino mass is exactly zero. The reason is that the Higgs is a doublet like the left handed leptons, and choosing the gauge so that the VEV is (H,0), the only mixing between right and left handed leptons is in the first component of the lepton doublet--- the one that's called the left-handed electron. The left-handed electron and the right-handed electron pair up to make the massive electron, leaving the second component of the doublet, the left-handed neutrino, unpaired and massless. In order for the neutrino to be massive, it must mix with its antiparticle, and in order to do that, it must absorb two Higgs field for SU(2) and U(1) charge conservation to work out. This can't happen in a renormalizable theory.Likebox (talk) 22:33, 3 November 2008 (UTC)[reply]

Do you think that an effective-field-theory standard model with phenomenological neutrino masses and mixings can no longer be referred to as "the standard model"? —Preceding unsigned comment added by Bakken (talk • contribs) 22:54, 3 November 2008 (UTC)[reply]

What I'm saying is that the effective field theory standard model is not all that standard. What's the model? Do you introduce a two-higgs interaction with the leptons? Why not a four-higgs interaction too at a different scale? Or extra gradients? I mean, I think that the two-higgs one is correct, because I believe that the new physics comes in at the GUT scale, but that's just my opinion. Besides, the standard model that I read about in books doesn't include non-renormalizable interactions. Every once in a while, you see a "seesaw mechanism", which is effectively the same as a phenomenological neutrino mass or a non-renormalizable interactions, but that's in GUTs, and that's an extension of the standard model. But why should we quibble about terminology. So long as there's a Lagrangian with neutrino masses that you have in mind which is the "standard model with neutrino masses", then I guess its standard. But I don't know what Lagrangian that is.Likebox (talk) 23:05, 3 November 2008 (UTC)[reply]

<quote>What's the model?</quote> Well, the least-effort model: the standard standard model with minimal Higgs fields, plus minimal-effort purely phenomenological neutrino mass term with Pontecorvo matrix or whatever it will be called. For me that sounds as a small correction. However from the introduction I get the impression that the standard model is nowadays experimentally proved to be "incompatible" and has to be discarded... :( (Bakken (talk) 23:38, 3 November 2008 (UTC))[reply]

Can I add that it is my impression that the standard model can not be easily tweaked to include non-zero neutrino masses, since RH neutrino terms are not possible within the SM? Perhaps the mass terms have to be added via some GUT scheme -- but that would be beyond the scope of the standard model which is explicitly not a GUT. --Michael C. Price ^talk 02:59, 4 November 2008 (UTC)[reply]

Yeah--- that's the picture--- you can describe phenomenological neutrino masses with a matrix, but you can't add that to the standard model Lagrangian with a renormalizable term, because it would violate gauge-invariance.Likebox (talk) 03:43, 4 November 2008 (UTC)[reply]

Oh, well then, if you mean it. It seems though that folks are busy at the moment finding the parameters of the mass matrix and are not particularly concerned with the renormalizability... Anyway, I am satisfied with the introduction, thanks a lot. Bakken (talk) 20:17, 4 November 2008 (UTC)[reply]

What's the problem with a term identical to the one used to give the u quark mass but replacing the quark fields with the apropriate lepton fields? —Preceding unsigned comment added by Dauto (talk • contribs) 23:43, 28 December 2008 (UTC)[reply]

The problem is that for the leptons there is only one such term--- there is 1 left handed lepton doublet and one right handed lepton singlet, so if you write down a mass term for the leptons it will automatically give a mass only to the electron. The neutrino is the second left-handed component.Likebox (talk) 01:34, 29 December 2008 (UTC)[reply]

Sure, but nothing is keeping us from adding a second righthanded singlet to the theory. (Shall we call it a right handed neutrino?) Dauto (talk) 17:16, 2 January 2009 (UTC)[reply]

There is something keeping you from doing that. The right-handed quarks are color triplets with a nonzero U(1) charge, but the right-handed neutrino would be a color singlet, a SU(2) singlet, and have zero U(1) charge. This means that a right-handed neutrino is completely neutral, and can have a large Majorana mass without violating any gauge symmetry. In order to have a right-handed neutrino you need to fine-tune its Majorana mass to zero.

A chiral spin-1/2 particle which is charged in any gauge group cannot have a Majorana mass.

If you introduce a right handed neutrino with a huge Majorana mass, small Higgs mixing with the usual neutrino give rise to a teeny Majorana mass for the ordinary neutrino. This is the See-Saw mechanism for neutrino masses, and it works if there is a right-handed neutrino at the GUT scale. The masses are of the right order of magnitude.

Exactly my point. It works without the need for any non-renormalizable terms in the lagrangian Dauto (talk) 21:32, 2 January 2009 (UTC)[reply]

Yes, it does. But if you integrate out the right-handed neutrino to get the low-energy effective action, it is exactly the same as the leading order non-renormalizable term.Likebox (talk) 01:08, 4 January 2009 (UTC)[reply]

I agree Dauto (talk) 01:31, 5 January 2009 (UTC)[reply]

Matter vs gravitational radiation in the introduction[edit]

Somehow I believe this phrase

"These particles make up all ordinary matter in the universe, excluding gravitational radiation..."

is clumsy at best. By definition, as I understand it, matter is everything at the right-hand-side of the Einstein field equation, that is the source of the gravitational field. The gravitational field itself is not matter by definition. Therefore the phrase "matter, excluding gravitation" is rather badly formulated.

Again "ordinary matter" is also something not defined.

I suggest changing that sentence into "these particles make up all matter in the universe except for the dark matter". Is it OK? —Preceding unsigned comment added by Bakken (talk • contribs) 20:25, 4 November 2008 (UTC)[reply]

Yes, it's true, but what about black holes? You can have a pure gravity field which contributes to the right hand side, like if you make a gas of little black holes, they will gravitate the same as a gas of atoms, except they will collide a lot and produce lots of gravitational radiation. But if that radiation is small compared to the scale at which you are solving the Einstein equations, the gravitational radiation will start to look like a contribution to the right hand side. But you could also call it the left hand side. I would say its a bit of a judgement call how you break up Einstein's equations into "matter" and "gravity", because gravity is also matter.Likebox (talk) 23:48, 4 November 2008 (UTC)[reply]

well, my teacher told me quite the opposite, I am afraid, namely -- gravity is not matter, gravity can be reduced to zero at any point by a coordinate transformation, while matter cannot. Matter has symmetric energy-momentum tensor (which is the source of gravity), while gravity has not, it has a pseudo-tensor. Gravitational waves are a solution to the Einstein equations in vacuum, without any matter, without any right-hand-side. Bakken (talk) 00:12, 5 November 2008 (UTC)[reply]

See, the point is -- wikipedia is written for ordinary people to read and understand, it is not a scientific article. If I for one do not understand what is written in wikipedia -- it is a bad wikipedia :( Bakken (talk) 00:12, 5 November 2008 (UTC)[reply]

Gravity can be reduced to zero at one point, but that just redefines where the gravity is. It then gets to be nonzero somewhere else. So there's a bit of ambiguity regarding where the energy of gravity is located. But so what. Other matter doens't have this ambiguity, but it has other ambiguities that are analogous: if there's a current in a superconducting ring, there's a phase twist somewhere in the ring. Where's the phase twist? Is it on the left hand side? The right hand side? The answer depends on the gauge choice for the electromagnetic field. In this case, it's not as physical looking a quantity as energy that is different in different descriptions, so it might not make you as uncomfortable, but the whole idea is the same whether you have gauge theory or gravity.

As far as the "ordinary people" go, everyone is pretty much the same when trying to wrap their heads around this stuff. I think that if the articles are clear enough, then everybody will understand everything, not just a special class of people who managed to hunt down the knowledge.Likebox (talk) 00:31, 5 November 2008 (UTC)[reply]

Your argument is: yes, gravity is completely different from matter, but so what, I will still call it matter. I guess even if Einstein self would tell you "in my general relativity gravity is not matter by definition" it wouldn't help. I bet that as usual you won't be able to produce a reference to a texbook on general relativity where gravity is called matter. Bakken (talk) 01:56, 5 November 2008 (UTC)[reply]

It depends on the definition of words. If you define "matter" as anything on the right hand side of the equation, then of course gravity is not matter. But if you define matter as anything that gravitates, has a mass and energy, then Einstein would say that gravitational fields are matter. He even defined a stress-energy pseudo-tensor which was not invariant to define where the energy and momentum of a gravitational field is located. It was, naturally, different in different coordinate systems. But you are absolutely right that I don't really care what Einstein thought--- authority has no weight in physics.Likebox (talk) 05:54, 5 November 2008 (UTC)[reply]

It is not only Einstein -- you don't care what anybody else says. Imagine I take your approach, go and delete all your edits I deem inappropriate for Wikipedia. Indeed authority has no weight in physics, and you are not even an authority... Watch me! Bakken (talk) 09:12, 5 November 2008 (UTC)[reply]

I try to listen to everybody. I mean, if you don't like an edit, just revert, and we'll go back and forth until we both agree. I don't think the disagreements are particularly deep here--- it's just about wording. I am sorry if I offended you. The reason I didn't like "visible matter" is that it excludes neutrinos, and it included black holes, which you can see by lensing if they are close.Likebox (talk) 02:50, 6 November 2008 (UTC)[reply]

Well "visible" here basically means "having electric charge", which excludes gravitating stuff, like black holes and dark matter, and also indeed exclude neutrinos. However, the idea of this sentence is to say that the particles of the standard model pretty much make up the ordinary world around us, right? Than it is all right, I believe. We can, of course, precisely specify what is what but then the sentence would become long and clumsy and not suitable for the introduction. Bakken (talk) 10:10, 6 November 2008 (UTC)[reply]

Yeah, and by your argument you can also "see" the dark matter, and, generally, since gravity affects light, you can "see" anything which has energy. Bakken (talk) 10:38, 6 November 2008 (UTC)[reply]

Arguments based on which side of Einstein's equations a term appears are not conclusive. Is the cosmological constant matter? It can (and does) appear on either side of Einstein's equations - it's just a matter of convention. And, yes, gravity can be transformed away by a coordinate transformation to zero at any point; but so can kinetic energy -- and even particles can be transformed away (see Robert M Wald's "Quantum Field Theory In Curved Spacetime And Black Hole Thermodynamics").

The way I see it it is purely a matter of viewpoint. Classically we think of gravity as a field ("geometry" rather than "matter") but we also believe it to be a particle (hence "matter"). I would say it is both. --Michael C. Price ^talk 07:05, 6 November 2008 (UTC)[reply]

Electromagnetic field cannot be transformed away by a coordinate transformation. If there is electromagnetic field at a point, no change of coordinates can remove it. The electric field can change to magnetic and back, but there will always be electromagnetic field in all frames of reference. While gravitational field can be removed by a coordinate transformation. Matter has energy-momentum tensor which is the source of gravitation. If it is a viewpoint, the why can you not accept the viewpoint of Einstein? Is there anything wrong with it? Bakken (talk) 10:10, 6 November 2008 (UTC)[reply]

Both POVs (which includes Einstein's) are correct. Where you draw the line between matter and gravity is not always clear. --Michael C. Price ^talk 12:06, 6 November 2008 (UTC)[reply]

well, you can of course call everything matter, but why would you want to do that? Then you will have matter of two types: the matter in the old definition, which has energy-momentum tensor and which contributes to the curvature of the space, and then the "gravity-matter" which has no energy-momentum tensor and does not contribute to the curvature of the space, because it *is* the curvature of the space.

If everything is matter, than why do we need this word at all? Why not just use the word "everything"? Bakken (talk) 22:52, 7 November 2008 (UTC)[reply]

Who knows, who cares? Not me. I was just pointing out that the arguments provided to support the distinction are not as water-tight as might they might appear. (Analogy: mass and energy are equivalent by SR, yet we still use the terms in different ways.)--Michael C. Price ^talk 00:45, 8 November 2008 (UTC)[reply]

I want to add--- while technically you could say that gravitational waves do not contribute to the local stress energy tensor, this point of view might make you think that they don't contribute to the total energy momentum, so that gravitational waves can't take away energy from orbiting neutron stars or something. This is completely wrong, but it was a point of view held by Eddington and one of Einstein's collaborators (I believe it was Nathan Rosen, but I'm not sure). Because of this, there was confusion until the 1950s about whether gravitational radiation carries energy.

The confusion was mocked (and ended) by Richard Feynman, who gave a simple example of a system which can absorb energy from gravitational radiation. It was a ring on a stick, and when gravitational radiation hits the ring, it can move against the stick, dissipating heat. This example ended the debate among reasonable people (but the debate should never have started in the first place, but anyway), but Rosen went on denying that gravitational waves carry energy well into the seventies.

At the same time, the whole of General Relativity was derived by Robert Kraichnan as a theory of a self-interacting spin-2 field coupled to its own stress energy tensor. In this point of view, the nonlinear parts of the Einstein equations are gravity being made by the energy in the gravitational field. This point of view shows that it is consistent to view gravity as a spin-2 field with gravitons carrying energy momentum same as any other matter. The problem with this point of view is that it is not background independent--- how you split up the gravitational field into linear part and nonlinear part depends on the choice of background around which you are perturbing. This is related to the problem of localizing energy-momentum in GR. That's equally background dependent.

The second issue with denying that gravity is matter is that neutral black holes are pure gravity. They are vacuum solutions, so there is no stress energy at any point (except maybe at the singularity, but that depends on your philosophy about whether the singularity is part of the manifold, and most relativists would say it isn't) but the whole thing has mass. The total energy momentum is nonvanishing, even though the local stress-energy is zero at any point. This type of thing is why the division between "matter" and "gravity" is not clear cut.Likebox (talk) 15:58, 8 November 2008 (UTC)[reply]

Nobody questions that gravitational waves can carry energy. It is well explained in textbooks on general relativity. Using the word "matter" as a synonym of "everything" is possible, but not generally accepted. By the way, the wikipedia's definition of "matter" excludes gravity. I hope, you are not going to go and mess up also that article... Bakken (talk) 16:36, 8 November 2008 (UTC)[reply]

I mean, this whole thing is just a political debate. You can call "matter" only quarks and leptons and gluons, and exclude light too. It's up to you how you use these words. The point is that the underlying mathematical structure should be made clear by your word choice. In this case, I think the current wording is clear. But I don't want to exclude gravitons from "matter", because there were people historically who were confused about whether gravity carried energy. Nobody is confused anymore, and the article should make that clear.Likebox (talk) 20:46, 8 November 2008 (UTC)[reply]

No, you can't really exclude light from matter as it has energy-momentum tensor which is the source of gravity similar to massive particles. Bakken (talk) 12:34, 9 November 2008 (UTC)[reply]

And this is just as true of gravitons. They have energy and momentum, and if you looked at a beam of gravitons gravitationally you would not be able to tell it apart from a beam of photons.Likebox (talk) 18:54, 9 November 2008 (UTC)[reply]

That's a very nice way of putting it. --Michael C. Price ^talk 19:42, 9 November 2008 (UTC)[reply]

By the way, if you take a glance at the TOC, you'll notice a section entitled Particles of Matter. It seems clear that based on the content of the section, "matter" in this article is referring to the fermions (quarks and leptons), and not to the bosons (photons, Ws, Zs, gluons, higgs, and especially the graviton). TriTertButoxy (talk) 02:23, 12 November 2008 (UTC)[reply]

Leading Paragraph[edit]

The leading paragraph seems a little inadequate to me; the first four sentences tells us what the Standard Model is, and the last three about what the Standard Model isn't. I believe this ratio is disproportionate as there needs to be more sentences about what the Standard Model is.

The last paragraph tries to explain what the Standard Model lacks, and is not exhaustive (dark matter, for example, isn't mentioned). The Standard Model is missing too much and an exhaustive list in the intro would be inappropriate. Shortcomings of the Standard Model should probably be deferred to a section within the body of the article.

TriTertButoxy (talk) 02:40, 12 November 2008 (UTC)[reply]

U(1) global symmetry and Prediction of W/Z mass[edit]

Dear Sir, I have two questions about standard model. First, is U(1) global symmetry? Then, what is the shape of U(1) in geometry. Second, would you please show me how to predict W/Z mass by using standard model or SU(2) with Higgs mechanism/spontaneous symmetry breaking? In addition, please give some references regarding the above two questions. Thank you very much. Sincerely,Wanchung —Preceding unsigned comment added by Wanchung Hu (talk • contribs) 03:34, 5 January 2009 (UTC)[reply]

The U(1) symmetry of the Standard Model is a local gauge symmetry. Geometrically, the closest thing for a shape of the U(1) symmetry would be a circle. Dauto (talk) 19:44, 30 January 2009 (UTC)[reply]

Notation[edit]

Right now this article notation is a mess. Sometimes the hypercharge field is called B, sometimes it's called Y. The hypercharges themselves use different normalization at different points. The coupling constants are called y,w,and g at one point, but then g, g', and ? at a different point. This is not an exhaustive list of the inconsistencies, just a sample. I will try to clean that mess up. Anybody that would like to make any suggestions feel free to let me know here and I will take a look at them and try to keep as many people happy as I can. Thank You. I will start by making sure the article consistently use only one convention for hypercharge normalization. I like the one where the hypercharge of the lefthanded positron is +1. Any other suggestions? Dauto (talk) 19:16, 30 January 2009 (UTC)[reply]

The hypercharge field should be called B, whereas the hypercharge, as a quantum number, is denoted Y. That's pretty standard. --Michael C. Price ^talk 00:19, 31 January 2009 (UTC)[reply]

Neutrinos again[edit]

This keeps coming up: people are saying that the neutrino masses are easily incorporated into the standard model. But the name "standard model" suggests that it should be standard. That means it should be unique and precise. This means: renormalizable interactions only, with only the usual multiplets of quarks and leptons. Then the neutrino is exactly massless.

Extensions of the standard model to include neutrino masses are easy, if you introduce a very heavy right handed neutrino you add small neutrino masses. But you can do it just by adding a non-renormalizable Higgs-lepton interaction too. You can also do it a million other ways, in SO(10) guts, or extensions, whatever. The point is that if you leave the context of renormalizable models with the usual quarks and leptons, I don't think you can still call that the "standard model", precisely because there are many choices--- it isn't standard anymore.Likebox (talk) 19:48, 5 May 2009 (UTC)[reply]

Probably worth adding a subsection about neutrino masses that says exactly what you've said. It might also be worthwhile mentioning here, or at the SU(5) article, that minimal SU(5), the first extension of the standard model, also doesn't permit neutrino masses since it doesn't admit right handed neutrinos.--Michael C. Price ^talk 15:53, 16 May 2009 (UTC)[reply]

Yes, neutrino masses can be added to the Standard model in many different ways, but only a couple of those are standard-model-like enough to be described as a simple extension of the standard model. The only important open question is "Should the (new) standard model include neutrino majorana masses or not?" The favored anser to that question is Yes!. Dauto (talk) 18:05, 19 October 2009 (UTC)[reply]

Number of parameters is now 27+1[edit]

Since the discovery of neutrino mixing the number of free parameters has increased from 18+1 to 27+1. Please see: http://online04.lbl.gov/~rncahn/18params_oct_2006.pdf --24.186.196.7 (talk) 06:25, 8 September 2009 (UTC)[reply]

If the right handed neutrino masses are included, you get 30 parameters. Interestingly, 22 of those are part of the Higgs sector of the theory. Food for thought. Dauto (talk) 18:24, 19 October 2009 (UTC)[reply]

Gravitons?[edit]

Can someone explain why gravitons are not mentioned in the article? The Higgs is of course, though it is also hypothetical. Is this because the Higgs is still required/predicted by the Standard Model, whereas the graviton isn't? A bit out of my depth here. Col. Sweeto (talk) 00:48, 27 March 2010 (UTC)[reply]

Gravitons are not part of the standard model. The standard model does not include gravity. It is a theory of matter, electromagnetic interaction, weak interaction, and strong interaction, period. Dauto (talk) 23:24, 30 March 2010 (UTC)[reply]

"Predictions of SM"[edit]

The comparison of measured and "predicted" mass of Z-boson is totally misleading. In fact what is called here "prediction" is actually an output of the so-called "global fit", which includes all available information. Including the measurement of MZ itself! The table actually compares the measurement with something which is completely dominated by the same measurement. The precision of direct MZ measurement is by far superior to any other contribution to our knowledge of MZ. This explains why measured and "predicted" errors are identical, and why the central values are almost identical.

I suspect that the same mistake was also done for the MW "prediction". If "prediction" is taken from the global fit, then it also includes the direct measurement. —Preceding unsigned comment added by Joyko (talk • contribs) 05:41, 23 April 2010 (UTC)[reply]

Neutrinos: mass and decay[edit]

The last sentence of the section on fermions states that "Neutrinos of all generations also do not decay". How does "neutrino oscillation" differ from decay? Are there other places in this section where the discovery of neutrino mass and oscillations need to be folded in? When is it (or will it be) appropriate to include the modifications associate with neutrino mass into a "standard feature" of the Standard Model. —Preceding unsigned comment added by Wcmead3 (talk • contribs) 15:07, 29 May 2010 (UTC)[reply]

Higgs (weak) hypercharge[edit]

Just came to this page to look up the weak hypercharge of the Higgs field. In the "field content" section the article says the Higgs is an SU(2) doublet with a U(1) hypercharge of -1. But in the "Higgs sector" section it gives the hypercharge as +1 (which is at least consistent with the electric charge assignment). I guess the problem is that different editors have used different (arbitrary) conventions but I'm only just getting my head around this stuff so wouldn't know which is the "best" convention to use throughout this article. It would be good if some agreement could be reached for consistency's sake though. 86.153.216.223 (talk) 22:04, 6 December 2010 (UTC)[reply]

Assessment comment[edit]

The comment(s) below were originally left at Talk:Standard Model/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

Missing list of major acheivements. Tompw 12:50, 5 October 2006 (UTC)[reply]

Last edited at 20:13, 15 April 2007 (UTC). Substituted at 15:51, 1 May 2016 (UTC)

Nature on standard model[edit]

"Yet its failure to account for phenomena such as gravity and dark matter leads many physicists to think that it is merely an approximation of another description beneath." http://www.nature.com/news/lhc-signal-hints-at-cracks-in-physics-standard-model-1.18307

should this be put into the article? — Preceding unsigned comment added by Vilagarcia (talk • contribs) 15:53, 10 September 2015 (UTC)[reply]

Total particle count[edit]

Elementary Particles
	Types	Generations	Antiparticle	Colors	Total
Quarks	2	3	Pair	3	36
Leptons	2	3	Pair	None	12
Gluons	1	1	Own	8	8
Photon			Own	None	1
Z Boson			Own		1
W Boson			Pair		2
Higgs			Own		1
Total number of (known) elementary particles:					61

I removed the "total particle count" section. The table that was in it is preserved on the right in case someone wants to try to derive something useful from it, but right now I think it makes little sense. It certainly isn't true that 61 has any special status as the "correct" number of Standard Model particles. To get this number, you have to treat particles related by some exact symmetries (gauge symmetries and CPT) as distinct, and treat particles related by other exact symmetries (continuous Poincaré) as equivalent.

Here are some ways of counting particles (in the SM with neutrino mass) that seem more principled:

If you count degrees of freedom of the field at a point, I think the best answer is 2 · 28 + 96 = 152 (see Luboš Motl's answer here, though he points out that you can argue for other numbers).
[Original research; I can't find a source for this:] If you count fundamental (pre-EWSB) fields that are not equivalent under any fundamental symmetry, you get H + G + W + B + 3 · (L + ν + e + Q + u + d) = 22.
[Original research; I can't find a source for this:] If you count post-EWSB particles that are not equivalent under any post-EWSB symmetry (essentially counting masses, except that gluons and photons are distinct), you get H + G + W + Z + γ + 3 · (ν + ν' + e + u + d) = 20 (assuming the Majorana coupling is nonzero; 17 if it's zero).

I don't really feel that it's useful to have any of these numbers in the article. They are the sort of thing that you memorize and regurgitate when playing Trivial Pursuit, not the sort of thing that is likely to provide any insight into particle physics. -- BenRG (talk) 03:44, 15 June 2016 (UTC)[reply]

Did SM really predict the W and Z boson masses ?[edit]

History section says "The W^± and Z⁰ bosons were discovered experimentally in 1981; and their masses were found to be as the Standard Model predicted.[citation needed]" but W_and_Z_bosons doesnt seem to confirm the prediction of boson masses. - ... (Standard_Model#Tests_and_predictions mentions the prediction but with no source.) - Rod57 (talk) 20:52, 2 September 2016 (UTC)[reply]

June 2013 comment above also queries this (says only the mass ratio was predicted) so the unsourced material was moved to that comment. - Rod57 (talk) 10:57, 6 September 2016 (UTC)[reply]

When was the Standard Model first defined and named as such[edit]

When was the Standard Model first defined and named as such ? [2] says "1974: In a summary talk for a conference, John Iliopoulos presents, for the first time in a single report, the view of physics now called the Standard Model. ... " Should we mention this in history ? - Rod57 (talk) 20:37, 2 September 2016 (UTC)[reply]

SM does not predict the number of leptons or quarks.[edit]

According to [3] "1976 : The tau lepton is discovered by Martin Perl and collaborators at SLAC. Since this lepton is the first recorded particle of the third generation, it is completely unexpected." - worth noting if verifiable with RS ? - Rod57 (talk) 20:46, 2 September 2016 (UTC)[reply]

The third generation was expected after CP violation was observed. "The Standard Model" means the model with three generations. Just 2 or more than 3 wouldn't be the SM. It is a bit tricky to talk about prediction if it is a matter of naming conventions. It is easy to extend the SM to more generations but then it is not the SM any more. --mfb (talk) 13:32, 13 June 2017 (UTC)[reply]

Tests and predictions[edit]

You would expect this section to summarise the current status of notable deviations from the Standard Model. Currently there are 2 poor attempts at summarising press releases about minor results without even mentioning their wider context. For example, the R(D*) anomaly is one of several anomalies in B decays, and BaBar isn't the only experiment to measure it. --Dukwon (talk) 14:59, 8 November 2016 (UTC)[reply]

Clearer image from CERN[edit]

I find that the current image at the top of the article could more clearly illustrate the connections between the fermions and bosons.

CERN standard model It has a more nuanced use of colour and negative space. Furthermore it more clearly associates the photon with the electron, the quarks with the gluons, and the mechanism producing neutrons with the neutrons.

In the current image these interactions are shown but they are a strain to discern for two reasons: the fact that they are forced into a single row and because of the lines being forced into the narrow space between the boxes.

The CERN charter states:

ARTICLE II : Purposes 1. The Organization shall provide for collaboration among European States in nuclear research of a pure scientific and fundamental character, and in research essentially related thereto. The Organization shall have no concern with work for military requirements and the results of its experimental and theoretical work shall be published or otherwise made generally available.

This seems to suggest that this material may be public domain. If so, we could use it directly. If not I would be happy to reproduce a similar image.

Craig Pemberton (talk) 03:34, 22 February 2017 (UTC)[reply]

Looks like a reasonable improvement in clarity, particularly in clearly presenting the underlying interactions (strong, weak, electromagnetic) that work with each elementary particle. Does it make sense to show the graviton though? The old Standard Model image used on the page did not show it, due to its hypothetical, yet-to-be-proven nature. DarthCaboose (talk) 07:50, 22 February 2017 (UTC)[reply]

That diagram seems to imply the photon and the gluon couple to the weak force. It shows that the quarks carry colour, but doesn't mention that gluons also carry colour. It also has the same problem with neutrino masses as the current diagram (quoting mass limits on the flavour eigenstates doesn't make sense). The spin and electric charge notation is inconsistent: there are zeroes on the neutrinos, but other zeroes (on the Higgs and gauge bosons) are omitted. There is no graviton in the Standard Model, so it shouldn't appear on a diagram representing the field content of the SM. Dukwon (talk) 09:21, 22 February 2017 (UTC)[reply]

There is a lot of CERN material that is not public domain, and the CERN charter is not sufficient to determine the status of that image. We can ask CERN. If we can use and modify it, I suggest the following changes to include Dukwon's points:

Remove the Graviton
Put the Higgs to the right of the Z. Change its mass to 125 GeV. Add its spin of 0. Extend the strong interaction box to the right, outside the weak interaction, and put the gluon in the new area that covers only the strong interaction.
The color of the gluon is indicated by the background color of the overall gluon box (in the same way the photon background matches the charge corner color), but maybe there is a better way to show this.
Keep the photon where it is. It couples to the W boson, that is electroweak enough to stay in the box I think. You could also call it electromagnetic, then the W has to move into the electromagnetic box. I think the current arrangement is better.
Make the 0 charge labels consistent, no opinion on the direction.
Make a conservative "<1 eV" for all three neutrinos. Yes, the flavor eigenstates are not mass eigenstates, but we know all three mass eigenstates are below 1 eV.

--mfb (talk) 15:55, 22 February 2017 (UTC)[reply]

(gravity is not an unsolved question, changed word order)[edit]

There is a recent edit with the edit summary: (gravity is not an unsolved question, changed word order). As far as I know, a theory of gravity consistent with both quantum mechanics and special relativity has not been solved. I won't revert, but someone might want to look into this. Gah4 (talk) 03:29, 9 April 2017 (UTC)[reply]

"Gravity?" is not an unsolved question - it is not even a meaningful question. "How to include gravity into QFT?" is one, but that is not the phrasing I changed. Gravity is a phenomenon not described by the SM, so I put the example of gravity next to the things not described by the SM. --mfb (talk) 13:09, 9 April 2017 (UTC)[reply]

Historical background[edit]

The historical background section is short. It does not give any context to the theory, and now the article reads as if the theory emerged for no reason in 1961. I tried to add some information on the prior development of thermodynamics and the discovery of the Big Bang theory, and how the standard model because of this has a different scope than classical mechanics. I directly quoted Lemaître's prediction of early universe high-energy particles and the context of this prediction. I also asked for a better explanation of the "theoretically self-consistent" claim. The idea of mathematical self-consistency was so harshly criticised by Kurt Gödel that I think a citation or a comment is mandated by who reverted my addition of a tag. Alternatively, we do not move into this metaphysical difficulty, but in that case the "Historical background" part will need to be renamed to "Background". Narssarssuaq (talk) 00:28, 5 November 2017 (UTC)[reply]

The Standard Model is the Standard Model of particle physics. Particle physics didn't exist at the time you want to add, and it was not the result of the events you want to add either. It was the result of lab and accelerator experiments and the study of cosmic rays. This has nothing to do with the big bang, thermodynamics, classical mechanics, or general relativity. Add these things to the cosmological standard model if you want (but leave out the classical mechanics stuff and thermodynamics please, they don't belong there either). --mfb (talk) 00:45, 5 November 2017 (UTC)[reply]

Thank you for your reply. "It was the result of lab and accelerator experiments and the study of cosmic rays" is an interesting way to put it. So they randomly figured out that they should do some random experiments based on random hypotheses and random observations and randomly came across a theory of almost everything? Not really, there was a historical and theoretical context to these observations and experiments, which in the dictionary genre may be of some relevance. I'll look more into the physics and see if I can contribute with something better than what I came up with, but it won't be now. Again, thanks for your valuable feedback. Narssarssuaq (talk) 01:13, 5 November 2017 (UTC)[reply]

No one said anything about randomness, although many discoveries were unexpected. What was driving particle physics was based on lab experiments, not based on cosmology. --mfb (talk) 01:33, 5 November 2017 (UTC)[reply]

OK, so it rests on no fundamental assumptions. That sounds like a perfect environment for circular reasoning, but I will not investigate this further now. Narssarssuaq (talk) 03:13, 5 November 2017 (UTC)[reply]

The fundamental assumption is that we can describe the world with physical laws. The rest is driven by experimental results. --mfb (talk) 02:15, 6 November 2017 (UTC)[reply]

hatnote[edit]

I just made a mess of the initial hatnote, in correcting the way it had been confounding between IIRC the topic and the article. I can't recall the proper format for my repl't hatnote, nor look it up on this iPad 2, nor at the moment wake up the quasi-real computer, so a colleague's correction of my blunder is a consumation devoutly to be wished.
--Jerzy•t 19:55, 1 December 2017 (UTC)[reply]

Anti-leptons not accounted for?[edit]

The article currently reads:

The Standard Model includes 12 elementary particles of spin 1⁄2, known as fermions. According to the spin–statistics theorem, fermions respect the Pauli exclusion principle. Each fermion has a corresponding antiparticle.

Those 12 are the 6 quarks, the 3 leptons and their 3 non-charged versions. Now, where are the positively-charged leptons (ie, positron, antimuon and antitau)? Are they not included in the standard model? --uKER (talk) 16:37, 14 June 2018 (UTC)[reply]

As it says, each has a corresponding antiparticle. They don't count separately, though. Gah4 (talk) 18:16, 14 June 2018 (UTC)[reply]

Despite that, the diagram explicitly refers to e−, μ− and τ−. Shouldn't the signs be removed and the mention changed that all three of them come in positive and negatively charged variants? Seems a bit arbitrary to explicitly mention the negative and neutral ones and leave the positive ones out. --uKER (talk) 20:59, 14 June 2018 (UTC)[reply]

We call some of them matter and the others anti-matter. As well as I know, the theory behind that isn't well understood, other than the lack of CP symmetry in the universe. I wouldn't complain about ± symbols, but others might. Gah4 (talk) 02:02, 15 June 2018 (UTC)[reply]

Yeah, I know what those particles are. I'm just trying to have the article make up its mind about whether the positively charged particles are considered and therefore needing to be mentioned or not. I always thought they were part of the model, but here the positive ones seem excluded. I'll go ahead and add those +/- signs. If anyone is against it we can always discuss it. --uKER (talk) 05:05, 15 June 2018 (UTC)[reply]

Publications usually write "unless noted otherwise the charge conjugated mode is always implied" or something similar the first time a particle is discussed. ± everywhere can be annoying, especially if you have more complex things where the charge of one particle depends on the charge of another or similar (∓). --mfb (talk) 05:22, 15 June 2018 (UTC)[reply]

I can agree with that, but if ± is to be avoided, then we should avoid the sign altogether. Listing e- explicitly and not e+ doesn't make any sense. --uKER (talk) 05:42, 15 June 2018 (UTC)[reply]

It is used for processes like

W^{-}\to e^{-}{\bar {\nu }}_{e}

where you want to keep track of what is what. --mfb (talk) 07:45, 15 June 2018 (UTC)[reply]

All chemistry and physics books about atoms indicate that they are made up from protons, neutrons, making up a positive charged nucleus and orbitals of negative electrons. The physics would be just fine if books indicated that the nucleus was negatively charged, made from antiprotons and antineutrons, with orbitals of positrons. Yes the physics would be fine, but we live in a matter world, not an antimatter world. The tradition is to name the matter particles, while indicating that antiparticles for them exist. Gah4 (talk) 07:33, 16 June 2018 (UTC)[reply]

Well, that's some progress. If the particles' antimatter counterparts aren't a part of the standard model, maybe a note is due saying so. As it is, it's kinda confusing to have the anti-particles mentioned as existing but then absent from the model's listing. --uKER (talk) 13:45, 18 June 2018 (UTC)[reply]

They are part of the Standard Model. --mfb (talk) 13:07, 19 June 2018 (UTC)[reply]

They are just implied. The only complication would be particles that are their own antiparticle. In the table, the photon, Z, and Higgs are their own antiparticle. I suppose it might be nice to indicate that. Gah4 (talk) 00:41, 20 June 2018 (UTC)[reply]

Lead diagram somewhat unclear[edit]

Following on from the above, the lead diagram implies there are two gauge boson particles, Z and W, whereas there are in fact three: Z, W+ and W-. It also suggests a single gluon particle whereas there are eight. Not an issue for knowledgeable readers, but confusing for anyone new to it, since the text appears to contradict the figure. Suggest modifying the figure to show W+ and W- separately, with overlapping tiles for the gluons. Pinging Cush. MichaelMaggs (talk) 18:46, 22 January 2019 (UTC)[reply]

It generally doesn't show particles and antiparticles (like W+ and W-) as separate objects - the quarks are only there once as well. It also doesn't show the quarks three times to account for different colors, that would be the equivalent of showing 8 gluons. The diagram shows the types of particles only. --mfb (talk) 22:14, 22 January 2019 (UTC)[reply]

@MichaelMaggs, the diagram is not meant as a substitution for the article. Additional shapes indicating color in quarks and gluons have been removed a few years ago. There is a chart showing particles distinguished by electrical charge here, but it is too big as the lead diagram for so many articles. ♆ CUSH ♆ 18:32, 23 January 2019 (UTC)[reply]

Diagram, again[edit]

Would it be sensible to include weak isospin and Goldstone bosons, or would this be to much for this rather simple diagram? Or maybe it would be good to include information from the diagram discussed above at Standard_Model#Diagram_of_Standard_Model_particles_and_interactions ♆ CUSH ♆ 18:20, 11 February 2019 (UTC)[reply]

Incorrect Interaction Diagram[edit]

I noticed that the interaction diagram is incorrect because it does not show that a Higgs Boson interacts with Neutrinos. The diagram needs to be removed and replaced with a correct one. Grayghost01 (talk) 16:09, 20 July 2019 (UTC)[reply]

It is unclear where neutrinos get their mass from. So far it looks like they have their own mass generation mechanism, independent of the Higgs. --mfb (talk) 00:06, 21 July 2019 (UTC)[reply]

Number of particles- 17, 25 or more?[edit]

I often see the number 25 quoted for the number of fundamental particles even though our diagram implies 17.[[4]] 25 breaks down to 6 quarks, 6 leptons, 8 gluons, the Z boson, the W+ and W- bosons, the photon and the Higgs. I understand there's a few ways of counting this depending on how you include antiparticles, but at least we should acknowledge this "25" number as the commonly given number, and maybe explain other numbers. I did add this 25 number to the article but it was reverted. Volunteer1234 (talk) 02:17, 3 October 2019 (UTC)[reply]

There are 17 little boxes in the infobox. Antiparticles are not double counted, so W+ and W- don't count separately. Also, particles with different color charge don't count separately. There are 6 quarks, not 18 or 36. (The latter including anticolors.). So also, gluons of different colors don't count separately, so they only count as one. Not completely obvious, but that seems to be the way it is. Gah4 (talk) 06:01, 3 October 2019 (UTC)[reply]

So why is 25 the number most often given? [[5]] Volunteer1234 (talk) 16:06, 3 October 2019 (UTC)[reply]

Also it's not up to us to decide how to count them, we should just state the number or numbers most often given and reference them. Volunteer1234 (talk) 17:17, 3 October 2019 (UTC)[reply]

120 results for 25, 788 results for "17+fundamental+particles". I don't see how you come to the conclusion that 25 would be the most common number. Anyway, every counting method comes with problems, unless we have to we should avoid counting, and if we have to we should explain the method used. --mfb (talk) 20:05, 3 October 2019 (UTC)[reply]

Status of gravity[edit]

When I talk to non-particle-physicists and non-physicists about what is and isn't understood in fundamental physics, I want to say something to the effect of

The standard model plus gravitons is a predictive and (as far as anyone knows) correct theory of fundamental physics that applies almost everywhere in the universe except for weird situations like exploding microscopic black holes or the Big Bang, situations that don't come up in the solar system, let alone in everyday life.

I'm not sure if that statement is exactly right or not, and this article doesn't really address it. So I guess my questions are: Is something like this statement true? If so, what are the exact situations in which "standard model plus gravitons" ceases to be a predictive & correct theory, ideally with those "situations" described in a non-technical way?

If it's true that "standard model + gravitons" is a predictive theory of all four forces, at any realistic measurement accuracy, everywhere on Earth and everywhere in the solar system ... but the article just says "The model does not explain gravitation", well I feel like the article is severely underselling the standard model in a very misleading way. --Steve (talk) 13:12, 30 April 2018 (UTC)[reply]

Standard model plus general relativity. If you plug in gravitons in calculations you run into all sorts of problems unless you add your knowledge from general relativity to predict what should come out. The SM does not include gravity, that is a correct statement. It is equivalent to "electromagnetism does not include the strong interaction". Different things. --mfb (talk) 14:37, 30 April 2018 (UTC)[reply]

Yes, that's why I wrote "standard model plus gravitons". I remember from QFT class that there is such a thing as "standard model plus gravitons". I remember doing homework problems with Feynman diagrams of spin-2 gravitons scattering off of electrons etc. I am asking about the class of situations in which these types of calculations can be done and give predictions in agreement with experiments. I'm quite sure the answer is not "never". I vaguely remember that it only works when graviton interactions are at the tree-level or something like that, and I'm asking for confirmation, and for what situations that corresponds to in the real world. --Steve (talk) 19:01, 30 April 2018 (UTC)[reply]

There already are articles dealing with the subject at Quantum gravity, Unified field theory, and Physics beyond the Standard Model. There is also a chart for that here. ♆ CUSH ♆ 18:37, 23 January 2019 (UTC)[reply]

The graviton is listed under 'spin 1' bosons, please change it by adding a spin 2 box. — Preceding unsigned comment added by 79.117.33.50 (talk) 16:56, 13 February 2020 (UTC)[reply]

I removed it completely as it doesn't belong here. --mfb (talk) 00:10, 14 February 2020 (UTC)[reply]

mixing[edit]

It seems that there is no discussion related to Neutrino_oscillation, or quantum mechanical mixing in general. This also complicates counting. Since the matter and antimatter particles (states) are not always the eigenstates, it does seem to make sense not to count them separately. Gah4 (talk) 22:06, 3 October 2019 (UTC)[reply]

It doesn't matter if you count mass or flavor eigenstates, the number is the same in both cases. For elementary particles antiparticles and particles don't mix with each other, this only happens for composite particles like mesons. --mfb (talk) 01:56, 4 October 2019 (UTC)[reply]

Yes. I think I don't understand neutrinos enough to know, but otherwise yes. Well, since quarks only exist in composite particles, you can't ask what they do alone. As far as I can tell, though, there is no article that really describes mixing and mixing angles. Gah4 (talk) 04:25, 4 October 2019 (UTC)[reply]

You can ask what valence quarks do and there is a clear answer. Quark-antiquark transitions would violate baryon number conservation (and also violate color charge conservation). --mfb (talk) 12:07, 4 October 2019 (UTC)[reply]

Updated Standard Model Interactions[edit]

The picture showing the Standard Model vertices does not include Higgs vertices (I assume this is because of it's upload date in 2011 being before the Higgs was discovered so it was chosen not to include it). It does not make much sense now to have a picture of Standard Model vertices and exclude the Higgs. In addition the picture is a fairly low quality .png . I have attempted to upload a .pdf image which includes all the Standard Model vertices including the Higgs, Page 13, Figure 2.6 from here http://cds.cern.ch/record/2746537/files/CERN-THESIS-2020-219.pdf , with the description

"The above interactions form the basis of the standard model. All Feynman diagrams in the standard model are built from combinations of these vertices. The first row are the quantum chromodynamics vertices, the second row is the electromagnetic vertex, the third row are the weak vertices, the fourth row are the Higgs vertices and the final row is the electroweak vertices.
$q$ is any quark, $X^{+/-}$ is any charged particle, $\gamma$ is a photon, $f$ is any fermion, $m$ is any particle with mass (with the possible exception of the neutrinos), $m_{B}$ is any boson with mass. For diagrams with multiple particle labels on one line, one particle label is chosen. For diagrams with coloured particle labels the particles must be chosen so there is two of one colour in the diagram. i.e. for the four electroweak boson case the valid diagrams are $WWWW$,$WWZZ$,$WW\gamma\gamma$,$WWZ\gamma$. 
The conjugate of each listed vertex (i.e. reversing the direction of arrows) is also allowed."

but I am not able to upload pictures. 81.107.39.90 (talk) 04:23, 16 January 2021 (UTC)[reply]

Incorrect Illustration of Interactions of the Standard Model[edit]

The image used in this article here https://commons.wikimedia.org/wiki/File:Elementary_Particle_Interactions.png has multiple mistakes with the electroweak bosons. The four electroweak boson vertices have been ignored, i.e. the photon and Z have directly self interactions through the yyWW and ZZWW vertex so there should be an arrow from the photon to the photon, and from the Z to the Z. In addition the photon and Z have a direct interaction with each other through the ZyWW vertex, so there should be an arrow between the photon and Z.

Ontop of this, the W is labelled as self interacting in this, presumably because of the WWy and WWZ vertex (since the four electroweak boson vertex self interaction for the others have not been considered), however in the same way that there is WWy and WWz, there is eey, eeZ (and other fermions) hence the fermions should all have a self interacting arrow as well.

Ontop of this there are numerous misleading but not strictly wrong things, for instance the choice to label the charge of the W but not the charged leptons, or label the neutral charge of the Z and H but not the other neutral bosons.

Ontop of this to someone not familiar with the topic, it implies that the graviton is part of the Standard Model ( Interactions of the Standard Model including the theoretical graviton makes it seem like the theoretical graviton is included in the Standard Model), and even if it was made more clear that the graviton is not included in the Standard Model, it is not an appropriate place for it to be considering it is very speculative and there are other connections that many would consider less speculative that aren't included (e.g. a direct coupling between the Higgs and the neutrinos). Note, I do not think a direct coupling between the Higgs and neutrinos should be included either (since this is not part of the Standard Model), but if we are including Beyond Standard Model effects there is no reason to include the graviton but not this (hence the graviton should be removed).

Also ontop of this, I am not sure what the rules are for "Descriptions" for images, but I do not think the description is appropriate, particularly this line "Note that the illustration has very obvious fivefold symmetry (pentagon and pentagram); perhaps this implies that the underlying physical theory of a Standard Model containing the Graviton gives rise to this pattern and may exhibit fivefold symmetry itself." which very clearly violates WP:NOR and is close to pseudoscience.

Overall with all the problems with this, this should be removed or remade. 81.107.39.90 (talk) 06:36, 16 January 2021 (UTC)[reply]

I have just noticed there is essentially an identical other image also on the page, https://commons.wikimedia.org/wiki/File:Elementary_particle_interactions_in_the_Standard_Model.png , that contains the exact same information with the same mistakes but it just presented slightly differently. 81.107.39.90 (talk) 06:54, 16 January 2021 (UTC)[reply]

I have removed these diagrams since they have so many issues and even if they were updated to not have these issues, they do not include any information that an updated File:Standard_Model_Feynman_Diagram_Vertices.png (which I have provided in the talk section above) does not include more clearly anyway. 81.107.39.90 (talk) 06:59, 16 January 2021 (UTC)[reply]

Quark charges[edit]

Why quark charges are not parameters of the S. Model? — Preceding unsigned comment added by 191.183.139.188 (talk) 02:03, 8 February 2021 (UTC)[reply]

The parameters listed are real values that can be continuously adjusted, so they don't include things like the quark charges which are rational numbers and are fixed at exact values. (e.g. if you try to change the down-quark charge from 1/3 to 0.333 then the theory breaks.) Patallurgist (talk) 04:58, 10 February 2021 (UTC)[reply]

Weak interactions act on flavour?[edit]

In the table listing fundamental interactions it says that the weak interaction "acts on" flavour. I feel like this isn't entirely accurate. The W bosons act on weak isospin and the Z bosons act on a combination of weak isospin and electric charge. While weak interactions can change flavour quantum numbers, saying that the weak interaction acts on flavour, would imply that the interaction only depends on the flavour numbers (or species), as electromagnetism depends on charge. This neglects the fact that weak interactions also depend on chirality. --Lukflug (talk) 18:24, 19 June 2021 (UTC)[reply]

Seems to me that acts on would apply if there was dependence, but not the only dependence. Yes electromagnetism only couples to charge, but that doesn't mean that others can only couple to one thing. Gah4 (talk) 01:26, 20 June 2021 (UTC)[reply]

Sorry, my terminology might not have been very precise. What I meant by "depends on" a certain quantity, is that the coupling is proportional to that quantity. I was just trying to argue that flavour is not analogous to electric charge in that case and it might make more sense to put weak isospin (at least for charged current interactions), since the coupling is directly proportional to this quantity. "Flavour" also isn't a clearly defined quantity. Not every flavour quantum number plays a role in the coupling strength, only weak isospin and weak hypercharge do. None of the "strong" flavour numbers, like Strangeness and Charm, play a role in the overall coupling strength to a particular particle (since the CKM matrix is unitary).

So, in conclusion, W bosons only couple to particles with weak isospin (the linear combination of photon and Z boson which couple to W bosons is part of the isospin triplet) and Z bosons only couple to particles with

T_{3}-Q\sin ^{2}\theta _{W}

. Saying that the weak interaction couples to flavour isn't wrong, but it might make sense to specify which flavour number. --Lukflug (talk) 11:28, 20 June 2021 (UTC)[reply]