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etymology

Should the article discuss the naming of the different quarks? Since the quarks have such odd names, I think many readers will wonder how they came by these names. Even if the labels are somewhat arbitrary, there still are reasons why these names were chosen. These are typically the fun factoids people try to look up in an encyclopedia. If we are going to introduce such a section we would need proper reliable sources since there is a lot of nonsense floating around on this subject. This webpage from fermmilab (physics folklore may not consitute a reliable source by itself, but the sources it cites might. Unfortunately I don't have access to any of those books. (TimothyRias (talk) 12:44, 17 July 2009 (UTC))

I disagree with an inclusion of this. The overwhelming majority of the material claims the names were almost completely arbitrary, and to claim otherwise here is almost misleading. There is no impulsion to read deeper into it. Names had to be chosen; and they were. —Anonymous Dissident^Talk 12:53, 17 July 2009 (UTC)

It is not like MGM choose "up" and "down" by random selection from a dictionary. If I recall correctly his original paper he explicitly says that "up" and "down" represent the up and down component of the isospin doublet. (interesting his third particle 's' stands for (isospin) singlet.) The reasons for calling 's' "strange" are also well documented. Charm is possibly the most random of them all, showing a Glashow and Bjorken being very pleased with their idea. Top and Bottom reflecting the fact that they mirror Up and Down also is very uncontroversial. Truth and beauty are again more random, but it should noted that these names were only introduced after the particle had being introduced as t(op) and b(ottom). There is nothing misleading about explaining where particles got their names and who gave them (although the last part is sometimes hard to track down). (TimothyRias (talk) 13:05, 17 July 2009 (UTC))

It's very clear that this is all trivia. We can hardly say in an encyclopedia article, "Glashow and Bjorken were very pleased with themselves, so they called it charm." That's why I would prefer to leave it out. Reliable sources in this area are very difficult to locate as well, and it's hard to know what to believe. Remember: verifiability, not truth. —Anonymous Dissident^Talk 13:10, 17 July 2009 (UTC)

Well apparently "We called our construct the 'charmed quark', for we were fascinated and pleased by the symmetry it brought to the subnuclear world." is a direct quote from Glashow, published in The Hunting of the Quark by Michael Riordan. I agree that it is a vague statement by the man, but it nicely illustrates how random that naming was. (As an interesting side note, he is actually talking about the charm quantum number, which in turn give its name to the corresponding quark.) This discussing this sort of thing will give a much better context for the current 'tag on' note about beauty and truth. (TimothyRias (talk) 13:37, 17 July 2009 (UTC))

Dunno about the original paper, but J.J. Sakurai in his QM textbook mentions the same reasons for the names "up" and "down". I would not object to adding a very short paragraph about the etymologies of flavor names in #Etymology (although I wouldn't use a wording such as "very pleased with themselves"). A rough sketch: "The names up and down represent the "up" and "down" components of the isospin doublet.[MGM][JJS] The strange quark is named after strangeness, a property of certain hadrons which was then explained as the presence of a strange quark;[3] according to Murray Gell-Mann, the symbol "s" also stands for "isospin singlet".[MGM] [Insert suitable wording for the naming of charm here.][4] Kobayashi and Maskawa originally named top and bottom quarks by analogy with up and down quarks,[KM] but the names truth and beauty, proposed by Gell-Mann, were commonly used in the past; now they have mostly fallen in disuse.[6]" (Other info about puns such as "the SM has beauty but not truth" would belong to the articles about individual flavors, if anywhere.) But that wouldn't be a vital part of the article, anyway. --A. di M. – 2009 Great Wikipedia Dramaout 13:30, 17 July 2009 (UTC)

Hmmm... that actually examplifies a lot of the misinformation out there. I don't think KM introduced the names top and bottom. Their names for the extra particles were p and λ' inline with the names used in the GIM paper (p, n, λ, p' for up, down, strange, charm). To make things worse one of the earliest uses I found of top and bottom were in a paper by MGM, who quotes Harari as having used it before. I've haven't really been able to figure out when people started using beauty and truth, but appears to be around the discovery of the b quark in 1977. (TimothyRias (talk) 13:49, 17 July 2009 (UTC))

Exactly. I implore you: leave it out. This is too wishy-washy an area. We cheapen the article and possibly introduce falsities here. The only ones we know surely and which (I think) we can source well are the top and bottom for the isospin doublets. —Anonymous Dissident^Talk 13:54, 17 July 2009 (UTC)

Additional note: I've thought about this some more. I suppose including quotes from key people to illustrate the name origins is not damaging, but we must be careful. I'll get to work on it tomorrow. —Anonymous Dissident^Talk 14:12, 17 July 2009 (UTC)

I've gone ahead and added a paragraph. I think it's long enough. All we need is a citation for Michael Riordan's book (the page number). I couldn't access it on GBooks. —Anonymous Dissident^Talk 15:07, 17 July 2009 (UTC)

Excellent. It's short enough that someone reading "Etymology" and thinking, "Why the heck should I care?" just needs to hit "PgDown" a coupla times to get to the next section header, and yet it includes everything the more curious reader will want to know (except the pun on "beauty but not truth", but that'd be way beyond the mark). Good work. --A. di M. – 2009 Great Wikipedia Dramaout 17:49, 17 July 2009 (UTC)

SM image.

The SM image suddenly doesn't show up anymore. Does anyone else have this problem? If I remove the 300px parameter, it shows up, but otherwise it doesn't.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 01:20, 18 July 2009 (UTC)

I had noticed that too, but I hadn't noticed about the removing the size param. I guess that's a (hopefully temporary) technical problem and am going to ask the Village Pump about this. --A. di M. – 2009 Great Wikipedia Dramaout 09:27, 18 July 2009 (UTC)

small question ;-)

Is the diameter of a quark larger than the Planck length? 4.249.3.140 (talk) 20:13, 22 May 2009 (UTC)

Yes, by orders of magnitude. A quark's diameter is ~10^-18m, while planck is 10^-35m. —Anonymous Dissident^Talk 23:39, 22 May 2009 (UTC)

The Standard Model quarks are pointlike (no spatial size) and as far as I know there is no experimental evidence to the contrary. Blennow (talk) 21:06, 24 May 2009 (UTC)

10^-18 is point-like. But it's not planck length. —Anonymous Dissident^Talk 21:36, 24 May 2009 (UTC)

No, 10^-18 is not point-like. It is very far from point-like. Point-like means no spatial extension at all, i.e., a diameter of zero. Just like all other elementary particles in the Standard Model. Blennow (talk) 22:38, 24 May 2009 (UTC)

Believe what you want. I can bring up at least a dozen sources in ten minutes supporting my assertion that quarks have a diameter of approximately 10^-18m. —Anonymous Dissident^Talk 06:00, 25 May 2009 (UTC)

Then you should probably do just that, because quarks like all fundamental particles in the standard model are pointlike objects. If the particles in the standard model would have a diameter, we would not have to worry about UV divergences en renormalisation, etc. since there would be a natural cutoff. I would not even know how to begin to define a diameter for fundemental particle, it is not like you can picture them as small hard spheres or something. The only thing that would come close would their interaction crosssection, but that strongly depends what type of particle the quark is interacting with, and also on the involved energies. So, I'm kind of curious what you mean when you say that quarks have a diameter. (TimothyRias (talk) 07:34, 25 May 2009 (UTC))

I'll just link a few for you; and that's just preliminary. —Anonymous Dissident^Talk 08:58, 25 May 2009 (UTC)

If you would have actually read that barrage of links of yours, you would know that that 10^-18m as just the experimental upper bound for the diameter of quarks. I.e. experiments have probed quarks down to 10^-18m scales and found no substructure and these results thus are consistent with the way quarks are modeled in the standard model, namely as point-like objects with zero size. (The two links that actual say that quarks are about 10^-18m in diameter are clearly talking out of their arse.) (TimothyRias (talk) 09:25, 25 May 2009 (UTC))

I don't think you've read them. A number of them state clearly, with no caveats, what I'm arguing. Concede or don't concede – I hardly care, and the IP can make up their mind for themselves. —Anonymous Dissident^Talk 09:31, 25 May 2009 (UTC)

Know what? I don't even think it's worth arguing. You're both trained physicists, and I'm just an amateur – what do I know? But those links do say that quarks are 10^-18. If I'm wrong, explain the direct way the sources are agreeing with me. Perhaps the conclusion to be made is that if quarks are finite, they are 10^-18m (approx.)? How else can the disparity here be explained other than to say there is more than one school of thought? —Anonymous Dissident^Talk 09:51, 25 May 2009 (UTC)

Well, you don't have to feel bad. The sources that say approx. 10^-18 instead of <10^-18, show that there are many people, some of them trained scientists, that have a hard time interpreting experimental results. The sources you linked that were actually written by particle physicists all agree that the 10^-18m figure is an upperbound. The other sources are mostly scientists from other fields (nuclear physics, geophysics and some relicrap) that either left out the nuance for simplicity or just misread the experimental result. Many people forget that if the result is <10^-18 this can mean anything from ~10^-19 to 0. (TimothyRias (talk) 10:08, 25 May 2009 (UTC))

This is what 10^-18 looks like .000000000000000001m. That is much, much smaller than a dot on a piece of paper that you can make with the point of a #2 pencil. Planck length has almost twice as many zeros to the right of the decimal point. I guess you can say the diameter of a quark is smaller than a decimal point, and the plank legnth is invisible compared to that. :-)

.00000000000000000000000000000000001m equals planck length. Ti-30X (talk) 04:48, 25 May 2009 (UTC)

Tim's right, 10⁻¹⁸ is the upper bound, but all elementary particles are pointlike (within the SM and probably all extensions of it, and within experimental error too). Headbomb {^ταλκ_{κοντριβς} – WP Physics} 12:46, 25 May 2009 (UTC)

Is there anything smaller than a quark and if so, what is the smallest "thing"? Livingston 16:16, 22 July 2009 (UTC)

Quarks are believed to be point-particles (no size). If that's true, then no, since you can't go lower than no size. But there are other point particles (see elementary particles for a list of them, all of whom are thought to be point-particles as well). Headbomb {^ταλκ_{κοντριβς} – WP Physics} 17:12, 22 July 2009 (UTC)

Perkins

One very tiny issue (as you know) is with the "According to Perkins" part. I really think it's needed because what is logical is a matter of opinion. We have to put quote marks around it, else it looks strange. And when we have quote marks, it's best to say straight away who is saying what. TRias seems to feel that this is "weaseling". What do you mean by that...? —Anonymous Dissident^Talk 13:40, 22 July 2009 (UTC)

The statement that the names 'top' and 'bottom' were chosen to be logical partners to 'up' and 'down' is not that controversial you can find any number of reference saying something along those lines (and we have a perfectly good one to boot). Any subjectivity of this logic lies with whoever made that choice (and nobody seems to know who that was, best I know Harari) in the first place. By presenting the statement as a quote your weaseling out of the responsibility of the statement. The fact that Perkins said that this is logical is nonnotable non-fact, this is completely irrelevant to this article, other than as a reliable source for the statement. So, if we are not going to make that statement there is also no point in presenting the quote.

Even if you want to weasel out of making the statement by putting it in quotes, it is still unnecessary to mention Perkins. It is clear that it is a quote from the ref standing right next to it. (to make this more clear you could put the ref before the period indicating it is sourcing the quote itself. Mentioning "Perkins (2000)" is a form of Harvard citation, while the rest of the article uses footnotes. (TimothyRias (talk) 14:03, 22 July 2009 (UTC))

Okay. I've decided I'm easy with it. I've resolved that we could go on all day making minor changes that are neither here nor there and that the average reader won't even notice, but that it's not worth it. The article's featured now, so that's something to be happy with, and I'm content to just leave it. —Anonymous Dissident^Talk 15:32, 22 July 2009 (UTC)

Mass

The mass section currently contains the following paragraph:

The masses of most quarks were within predicted ranges at the time of their discovery, with the notable exception of the top quark, which was found to have a mass approximately equal to that of a gold nucleus,^[1] significantly heavier than expected. Several theories have been offered to explain this very large mass. The Standard Model posits that elementary particles derive their masses from the Higgs mechanism, which is tied to the unobserved Higgs boson. Physicists hope that, in the next years, the detection of the Higgs boson in particle accelerators (such as the Large Hadron Collider) and the study of the top quark's interaction with the Higgs field might help answer the question.^[1]

citing:"New Precision Measurement of Top Quark Mass". BNL News. 2004. http://www.bnl.gov/bnlweb/pubaf/pr/PR_display.asp?prID=04-66. Retrieved 2008-09-24.  The only statement that seems to be supported by that ref is that the top quark has about the same mass as a gold nucleus. In particular, it doesn't speak about the top mass being a mystery or about studying the Higgs being expected to shine any extra light on that matter. If anything it talks about the opposite: precise measurements of the top mass being needed to study the Higgs. (Because it is an important parameter in many higgs processes.) I'm somewhat curious by what is meant that "the masses of most quarks were within predicted ranges at the time of their discovery" since the standard model doesn't predict any quark masses, they are free parameters. (or rather the coupling constants of the quark fields to the higgs field are free parameters; same difference). Moreover, I don't imagine that the very low masses of the up and down were expected at first. If there is any mystery here, it is that the quark masses span 6 orders of magnitude. For this there indeed speculative ideas about broken family/generation symmetries, and it is indeed hoped that the LHC will shed some light on this. But this is not what the current ref is about, nor is it what the article is currently saying. (TimothyRias (talk) 12:44, 8 June 2009 (UTC))

I remember wondering something like that either about the current version, or about a previous version. As you say, the standard model does not predict quark masses from first principles. What I suspect might be meant here is that the quark masses indirectly enter the cross-sections for some reactions other than resonances for the quark in question. If you observe these other reactions first, you might get some limits on quark masses, to be confirmed once your beam energy is sufficiently high to produce the appropriate resonances. But that would only apply to the heavier quarks–for the lighter ones, not much time seems to have passed between postulation and resonant production. Anyway, let's tone it down to what's actually in the reference. Markus Poessel (talk) 19:34, 8 June 2009 (UTC)

The main problem here seems to be the "predictability" or "non-predictability" of the top quark mass. The simplest solution is to simply remove any reference to prediction of any kind, which I've done. Fixed? —Anonymous Dissident^Talk 07:48, 9 June 2009 (UTC)

That doesn't really solve it. The article still suggests that the large top mass is something that needs explaining. (while apparantly the other quark masses don't need explaining?) Furthermore, the article completely leaves me in the dark to what theories it is refering that could solve this 'problem'. (hence there is a problem with WP:V, as I cannot verify that statement that the theories exist). Finally, the article is still quoting the BNL PR release for the statement that scientists hope that LHC detection of the Higgs will shine further light on the size of the top mass, while it is only stating the reverse: future precision measurements of the top mass, will shine light on the value of the Higgs mass.(TimothyRias (talk) 08:45, 9 June 2009 (UTC))

Fine. All fixed. I've removed all reference to the problematic article and have used two new sources. —Anonymous Dissident^Talk 09:00, 9 June 2009 (UTC)

That is much better. I made some minor tweaks. (TimothyRias (talk) 09:39, 9 June 2009 (UTC))

In [[1]] it is stated that mass of a proton is about 20 times larger that the total mass of its quarks. In this article it is stated that the equiv. mass of proton is 938 and the total mass of its quarks - 11, ratio of about 85. Is it an explainable discrepancy? —Preceding unsigned comment added by 130.199.3.130 (talk) 04:08, 26 July 2009 (UTC)

The other article was innacurate, so I've updated it. Citations and a note explain where you get the numbers from are still needed. Might get to do that tomorrow.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 04:53, 26 July 2009 (UTC)

FA

I'd just like to congratulate everyone who has consistently worked on this project on a job well done. It's been a long time coming, but I feel we've raised this article to a high standard. Special thanks go out to User:Markus Poessel, User:TimothyRias, User:Headbomb, and User:A. di M.. On a related note, I'd encourage everyone to leave the article as is now. That sounds hypocritical from me, given that I did make a few wording changes after the golden star was added, but I'd like to stress that we have to stop at some point. There's really very little point in tweaking with such things as section structure (ie. at Etymology) now. The formula works – it's Featured now. Thanks, —Anonymous Dissident^Talk 12:08, 22 July 2009 (UTC)

Congratulations to everyone. Working on this article has left me with quite a few good sources and ideas that can be used to improve the up quark, down quark, strange quark, charm quark, bottom quark and top quark articles. This probably true for the rest of you as well. So, I was wondering if any of you were interested in trying to improve those article to at least GA level as well? (TimothyRias (talk) 13:15, 22 July 2009 (UTC))

Congrats to all. It's been a long process, but what a result! I'm definitely interested in working on the Up to Top quark articles. I had the goal of bringing Lepton to FA article as a follow up to quarks (after we finally resolve that CKM image thing), as it would probably be very easy to copy the structure and flow of the quark article, but I'm not closed to the idea of working on the individual quark pages as well. The individual quark articles need more work right now, so I wouldn't object to working on them first. Baryon is also a good candidate to bring to FA, and meson ain't that far away either.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 15:48, 22 July 2009 (UTC)

"Electron" is a GA and was unsuccessfully nominated for FAC in January; what about that one? --A. di M. 14:43, 23 July 2009 (UTC)

Seems too hard to bring to FA IMO, just way too massive in scope compared to the other articles.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 22:05, 23 July 2009 (UTC)

Quark decays image

The six quarks' decay modes, with mass increasing from left to right. The "intensities" of the lines are dictated by the CKM matrix. It should be noted that the decay properties are inferred from those of quarks bounds within hadrons, except in the case of the top quark which decays too rapidly to form a hadron.

OK, we need to discuss this image. To me, it is completely unclear what this figure is supposed to portray. Is it decay widths of free quarks? Is it possible decays of bound quarks? Is it the elements of the CKM matrix? I don't know because as far as I can figure out it does not accurately portray any of those. This has been an issue for a long time and it now stands as one of the last issues for this article going to FAC.

As I see it the problems with this image can be traced back to one thing: It is not properly sourced. As a result nobody is able to check whether it is correct or not. To resolve the issue we need a couple of things:

1. A good description of what this image is supposed to portray on the image description page, including a description of what data is going into the image and what methodology was to create it. (For example why is there no arrow t -> u, a process allowed by the SM but suppressed because it involves 2 virtual W's)
2. Refs for that data.

(TimothyRias (talk) 22:02, 20 July 2009 (UTC))

It should convey the elements of the CKM matrix, in the context of quark decay (single W boson). I dunno how to make #1 clearer, and the refs for #2 is the matrix itself.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 01:34, 21 July 2009 (UTC)

Opinions on this?Headbomb {^ταλκ_{κοντριβς} – WP Physics} 04:47, 21 July 2009 (UTC)

So, the direction of the arrows in the diagram is based on the actual (hypothetical) decays of free quarks, while the strength of the arrows only reflects the size of the relevant element of the CKM matrix and ignores all the other factors that go into the decay width. I feel this is a bit weird Frankensteinian and prone to cause confusion with readers (like it did with cryptic). It would make more sense to have the arrow style be dictated by the actual decay widths of the free quarks. (Of course that would require a source giving these decay widths.) This would look a little different from the current diagram. First of all Γ(t->b) is much larger than any of the other decay widths, this would be a good place to show case that graphically. Moreover, due to the large mass difference Γ(b->u) is probably much bigger than Γ(d->u). (again my intuition, needs a proper source). (TimothyRias (talk) 09:16, 21 July 2009 (UTC))

What to the decay widths have to do with anything? The direction of the arrows is based on quark mass (high mass to low mass), and the intensities of the arrows are the coupling indicated by the CKM matrix elements.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 16:43, 21 July 2009 (UTC)

The fact that the description says that these are quark decay modes, will suggest to a lot of people that these are the decay widths (even to those that do not know what decay widths are.) It is very weird to be talking about decays one hand and then only show one ingredient going into the decay probability. (TimothyRias (talk) 22:24, 21 July 2009 (UTC))

How does it suggest anything with respect to decay width? Headbomb {^ταλκ_{κοντριβς} – WP Physics} 15:53, 22 July 2009 (UTC)

Just take a brief step back and look at the picture as if you are seeing it for the first time. You see some quarks and some arrows between them that represent the "decay characteristics". I would think (and I believe a significant amount of readers with me) that the arrows somehow represent the probability of each decay (aka the decay width). When you then read the description and learn that it is supposed to be the magnitude of the corresponding CKM matrix element, (some) people will be confused. (TimothyRias (talk) 13:41, 23 July 2009 (UTC))

Well the two are intimately related. The CKM magnitudes squared are the probabilities of these decays happening in a "hot soup of quarks" scenario, when nothing is suppressed by kinematics. Perhaps we could frame that image in that context? Headbomb {^ταλκ_{κοντριβς} – WP Physics} 15:20, 23 July 2009 (UTC)

In a hot soup of quarks the decays will go every possible way, since at high enough temperatures all the quarks are effectively massless. So that doesn't make much sense either. (Note that if we should conclude that the image needs some alterations I'm available to implement them.) (TimothyRias (talk) 15:28, 23 July 2009 (UTC))

(←) With arrows pointing both ways then? Headbomb {^ταλκ_{κοντριβς} – WP Physics} 22:03, 23 July 2009 (UTC)

That would be an option. Although I fear almost nobody will be able to appreciate the nature of that context. It also possibly suffers from being highly hypothetical in nature due to the high temperature involved. (To justify the assumption that the top is massless "the soup" would need a temperature of ~ 10 TeV, since there is a somewhat general expectation of new physics beyond 1 TeV this might turn out to be a very unrealistic scenario.)

An other option would be to replace the arrows with grayscaled solid arrows with the color proportional to the actual decay widths under the (unrealistic) assumption that the quarks are free. The problem with this option is that we would to find a source that actually calculates these decay widths. Alternatively, we could do the calculations ourselves providing the details on the image description page, but that would be horrible computation that I do not look forward to (maybe I can stick it to some grad students >:)). The calculation would also entail keeping track of the decay possibilities that open up for the higher mass quarks. (one of the reasons for the high decay rate of the top is the fact that it can decay to on-shell W's.

An easier option maybe to just indicate what the most probable decays are for each quark (under the caveat that they are assumed to be free). This hierarchy of branching ratios is not that hard to deduce, if we can't source it. Changes to the image would be minimal: some changes to the wording, the b->c, and s->u would become solid lines etc. We loose some information this way, most notably the fact that s and b are more stable than you would expect based on their mass alone due to the same values of the relevant CKM elements. (TimothyRias (talk) 08:50, 24 July 2009 (UTC))

Let's keep the image qualitative. It's meant to give a "visual feel" of the matrix. It should illustrate (for say a c quark) that in a hot quark soup, the c will change into an s most of the time, into an u some of the time, and into a t once in a blue moon. Another possibility is that we bite the bullet and use the term we're trying to avoid (coupling strength).Headbomb {^ταλκ_{κοντριβς} – WP Physics} 21:37, 24 July 2009 (UTC)

Yes, we could do that. Proposed changes: image heading: Quarks -> Quark weak interactions; lose arrowheads; legend: interaction strength, powerful, moderate, weak. Completely lose all mention of decays. How about that? (TimothyRias (talk) 09:17, 27 July 2009 (UTC))

I'd go further and even lose the heading. We can start the caption with "The strength of the weak interactions of quarks" or something similar. The only thing I don't like is the powerful/moderate/weak divisions, they don't have the right connotations. The right ones are strong/weak/weaker, but then there's confusion with a big/small coupling strengths and the strong/weak interactions. I say let's change everything but the strong/weak/weaker for now, so we can at least start fixing the image and its caption.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 16:29, 27 July 2009 (UTC)

The strengths of the weak interactions between the six quarks. The "intensities" of the lines are determined by the elements of the CKM matrix.

OK,how about this then. I've implemented the changes above. Furthermore, I've cleaned up the image (and the SVG code) to hopefully make it a little easier on the eyes for those of us with high DPI displays. I've gone with interaction strength: strong/moderate/weak, hopefully having the word 'moderate' there will limit confusion with 'strong interaction' and 'weak interaction'. (TimothyRias (talk) 10:04, 29 July 2009 (UTC))

That looks great!Headbomb {^ταλκ_{κοντριβς} – WP Physics} 13:42, 29 July 2009 (UTC)

Further tweaks on the image could be centering "Interaction Strength" in the box (small s in strength?), and decapitalizing Up-type and Down-type. I would also use a dotted line (instead of a spacier dashed line) for the weak line, to further enhanced the visual difference between the moderate/weak lines. Finally, the udcstb labels do not seem to be centered in their respective balls. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 15:33, 29 July 2009 (UTC)

Done. How does it look?Headbomb {^ταλκ_{κοντριβς} – WP Physics} 16:01, 29 July 2009 (UTC)

OMG inkscape raped my pretty SVG :( (TimothyRias (talk) 19:34, 29 July 2009 (UTC))

What exactly has been raped? It looks all nice and purrrdy on this end? Headbomb {^ταλκ_{κοντριβς} – WP Physics} 04:08, 30 July 2009 (UTC)

Compare the source code of my original upload with that of the current version and you might see why i'm sad. Especially if you consider that I usually edit SVGs with a text editor. (TimothyRias (talk) 05:51, 30 July 2009 (UTC))

Ah, well I can't see the source code (don't know how). Feel free to take your version and redo my changes in a non-rapist way. They should all be pretty apparent, except the removal of a duplicate line from s to t, and the centering of the udcstb labers withing their respective balls. I recall some diagonal lines not being of the same length and have to copy-paste the appropriately lengthy ones, but that might have been another image. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 07:56, 30 July 2009 (UTC)

(off-topic:To see the source code just open the SVG in any text editor.) (TimothyRias (talk) 10:26, 30 July 2009 (UTC))

How about this caption?Headbomb {^ταλκ_{κοντριβς} – WP Physics} 15:28, 29 July 2009 (UTC)

I would leave out the middle sentence. It is very cryptic even if you what is about. (It is also partially wrong, the V_ts and V_tu components are (currently) impossible to get straight from top decay and are currently obtained through precision measurements of processes involving virtual top quarks. Kaon decay?) It is enough to say that are the intensities are obtained from the CKM matrix, how exactly those matrix elements are measured is discussed in the PDG ref and is well beyond the scope of this article. (TimothyRias (talk) 19:41, 29 July 2009 (UTC))

Alright, so this version is fine for the article?Headbomb {^ταλκ_{κοντριβς} – WP Physics} 04:09, 30 July 2009 (UTC)

I think so. (TimothyRias (talk) 05:46, 30 July 2009 (UTC))

Uploaded.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 08:07, 30 July 2009 (UTC)

The strengths of the weak interactions between the six quarks. The "intensities" of the lines are determined by the elements of the CKM matrix.

I found an issue with the previous image. It suggested that the cd and cb couplings were virtual identical. I've created an alternative version to correct this issue by making all lines solid and having the color determined by the actual CKM values. I also created the SVG to actual be 271px wide to create less fringes on that resolution. (TimothyRias (talk) 10:26, 30 July 2009 (UTC))

An interesting take. For it to work however, we'd need to have a white (Vij=0, weak) to black (Vij=1, strong) gradient instead of three distinct level (black gray white-ish). (See the thing on the right of this plot if i am unclear [2]). The udcstb labels are still not centered within their balls. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 14:16, 30 July 2009 (UTC)

Added a gradient. Also, in a less-is-more spirit I've done away with the "interaction strength" text, leaving more space for the other elements. The labels look centered to me now. (also fuck buggy rSVG rendering engine used by MediaWiki). I'll check it on my other PC with a much higher DPI screen if this is legible, otherwise there is some room for increasing the font size. (TimothyRias (talk) 15:54, 30 July 2009 (UTC))

Great. Dunno what you did with the labels, but it looks good now. I'll switch the image in the main article, and we can finally move on to another one (see section about the next article somewhere on this talk page). Headbomb {^ταλκ_{κοντριβς} – WP Physics} 16:01, 30 July 2009 (UTC)

Actually, aren't you an Administrator? We should merge the histories of all versions of this image.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 16:03, 30 July 2009 (UTC)

No, not unless somebody made admin while I wasn't looking.:) (TimothyRias (talk) 20:08, 30 July 2009 (UTC))

Repeated linking of same terms

I've noticed some inconsistency in the linking of technical terms already linked in previous sections. For example, in "Classification" we link "electric charge" but not "spin", and in "History" "bottom quark" and "top quark" are linked but none of the other flavours is. Now, the "canonical" way of only linking a term the first time it occurs in the whole article is way too drastic, because not everyone reads the article entirely from the top to the bottom. OTOH, randomly deciding to link some terms and not others is weird, and linking technical terms whenever they occur is overlinking.

An idea could be to link each relevant term only the first time it occurs in the article, except "specialistic terms" which should be linked the first time they occur in each section, where by "specialistic term" I mean a term that most people with a high school diploma have never heard of. (So "electric charge", "gold", "Big Bang" and "point-like"/"point particle" would not be "specialistic terms", but "gluon" and "quantum chromodynamics" would.) What do you think? (BTW, what's the point of "See also" templates at the beginning of sections whose very first sentence contains a link to the same article?) --A. di M. 14:22, 26 July 2009 (UTC)

I'd agree with that linking rational. The see also section are there because they either point to the main articles, or to topics of high-relevance relative to all the links found in that section.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 14:37, 26 July 2009 (UTC)

Quark as 15 September 2009's TFA

Since it's Gell-Mann's 80th birthday, why not? Comments can be left on the TFA request page (click on the header to get there). Headbomb {^ταλκ_{κοντριβς} – WP Physics} 18:03, 15 August 2009 (UTC)

Apparently I have to wait a few days before nominating, so I removed it for now and will re-add in about a week time. I'll update this page when I do so.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 13:08, 16 August 2009 (UTC)

Alright, resubmitted. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 05:46, 25 August 2009 (UTC)

Do quarks exist?

Hi,

I just wanted to ask if quarks really exist.

I know this sounds like a but of a silly question, but I was recently reading a book by physicist Fritjof Capra, called "The Tao of Physics", and in the book he talks a lot about modern atomic physics, and he mentions a lot of quantum theories, including the quark theory, the s-matrix theory, the bootstrap theory, and the quantum electrodynamic/chromodynamic theories.

However, he mentions quite explicitly that there is no real reason to believe that quarks per se exist as actual fundamental particles. He says that it is a good theoretical model that explains a lot about our experimental observations, but no quarks have been observed, and no other particles have been known with a charge which is a fraction of that of the electron.

I also found this article on the internet: http://www.springerlink.com/content/87g2503m3754t066/ and in Andrew Watson's "The Quantum Quark", he mentions that

Gell-Mann himself argued that quarks, with their controversial properties, couldn't be seen individually, but only as composites having the better-behaved properties of particles such as protons and neutrons. In this way, fractional electric charges and baryon numbers were not "real" as such. [..] Is [the quark] a particle that experimenters can look for, or is it some mythical mathematical device useful for explaining a bit of group theory? (p.163, Cambridge University Press 2004) (also here: http://books.google.com/books?id=ip50x8IOfnEC&lpg=PA163&ots=uVzweNevmN&dq=quarks%20are%20not%20real&pg=PA163#v=onepage&q=&f=false )

"The Tao of Physics" was written in 1975, but it was revised and an afterword was written in 1995 so I would assume the information in it would be quite accurate, but it clearly might be wrong (more recent experiments might have discovered quarks).

If it is not certain that quarks really exist, is there a reason why by reading the wikipedia article one gets the impression that quarks are real, physical, fundamental particles, and not just part of a theory?

Of course I may be wrong, and quarks might have actually been physically observed in experiments, so please forgive me and correct me. (I don't have any reason to support or refute any of the theories, so I would be equally happy if someone provided links to articles which showed that experimental evidence of quarks exists.)

Thanks a lot :)

Jujimufu (talk) 09:28, 30 August 2009 (UTC)

This view was indeed very popular in the early days of the quark model and persisted deep into the 1970's. Since then quarks have become excepted as physically real objects. This is evidenced by many experimental observations ranging from the deep inelastic scattering experiments in the 1960's revealing that there must be some sort of partons later identified as quarks, formation of jets in high energy collisions, to the strong indications for the existence of a quark-gluon-plasma phase containing free quarks at high temperatures. Most of these are actually mentioned in the article. (TimothyRias (talk) 11:08, 30 August 2009 (UTC))

As TRias says, that view is quite obsolete. There is hard empirical evidence for quarks now, contrary to what your source says. —Anonymous Dissident^Talk 06:13, 15 September 2009 (UTC)

Yes. Also Gell-Mann has repeatedly been taken out of context in what he meant. He said he always considered them physical, but unobservable as free particles. This was interpreted by people who believed them to be mere mathematical artifacts to mean that he too thought of them to be nothing more than mathematically convenient, but not necessarily physical things. Communication being what it was in the the 1960 and 1970s, this idea that Gell-Mann didn't think of them as real entities spread around for a while. And since old ideas die hard, people still say that Gell-Mann didn't think they really existed or something. Of course, Gell-Mann's opinion on it is really irrelevant to whether or not they actually exist, but today I don't think anyone sees quarks as being any less real then electrons. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 06:28, 15 September 2009 (UTC)

Yes, Gell-Mann's opinions are irrelevant, except historically. But the reason why " people still say that Gell-Mann didn't think they really existed or something" is because he vacillated in the original article, saying (I paraphrase) that quarks "may be considered" as real. I think it was Zweig who said that Gell-Mann was trying to have his cake and eat it - i.e. covering himself if they didn't exist, yet ready to take the credit if they did - and it worked :-) .

important query ^_~

i'm pretty sure i saw this as a featured article not too long ago. whats up w that? ~_~ ~ —Preceding unsigned comment added by 68.198.35.90 (talk) 02:27, 16 September 2009 (UTC)

Ne'eman part in the QM

The history section conclude that Ne'eman independently formulate a scheme which is identical to the eight fold way (before Gal Mann actually, it's not mentioned here) but that he take no part in the subsequent proposal of the QM. This is factualy wrong, and if someone insist that such statement to be included (while in any case it's unneeded) he/she have to source it.

Ne'eman demonstarated before Gall Mann how practical proprties can be explained by symetry group SU3. Especially he showed how 8 Baryons can represent both neutrons and protons and anticipated the QM. If you claim otherwise, source it.--Gilisa (talk) 07:29, 15 September 2009 (UTC)

Article says Gell-Mann in the early 1960s (Gell-Mann worked on this since 1961 actually, but only published in 1964), and Ne'eman in 1962. I fail to say how this is not mentioning that Ne'eman came up with the Eightfold Way (who'se first is a matter of how you count, time of idea, or time of publication). Concerning the other thing, the quark model is from Gell-Mann and Zweig, not Ne'emann. The original articles from Gell-Mann and Zweig are given, plus the later article by Carithers et al. That's on top of all the other sources used in the article. I really don't know what more you could want. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 07:34, 15 September 2009 (UTC)

I'm out of my revert quotas on this topic, so if someone else could restore this, it would be nice. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 07:46, 15 September 2009 (UTC)

Well, it's only by the time of publication, meaning that Ne'eman should be mentioned first if you think on it. About the idea any one can tell anything he want others to think, it's obvious and there is no question here. Ne'eman started to work on the idea on the early 1960s and I deeply believe (after hearing the all story from late Ne'eman himself-but it's off the record of course, no original research intend) that he was the first. Actually, many think so. You argue that Ne'eman didn't anticipated the Quark model, so the burden of providing adequate source to support it is on your back (and you wrote that there are few in this article-so, please introduce one that indicate that in none of Ne'eman publications he anticipated the QM). --Gilisa (talk) 08:00, 15 September 2009 (UTC)

Do I also need to show that Lee Smolin didn't develop the Quark Model? Gell-Mann and Zweig proposed the quark model. What Ne'eman did is proposed the Eightfold Way. We're saying that he was not involved in the quark model to prevent confusing, since the Eightfold Way and Quark Model are related, but not the same things. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 08:12, 15 September 2009 (UTC)

You don't have to explain me what the QM is. You do have to source your claim that Ne'eman didn't anticipate the QM. The comparison to Smolin is funny.--Gilisa (talk) 08:14, 15 September 2009 (UTC)

Gilisa, it's on you to demonstrate that Ne'emon did propose the quark model, not on us to demonstrate that he didn't. All the sources I've seen have only gone so far as to say that Ne'emon was involved in the eightfold way. It's ridiculous to ask us to find sources stating that Ne'emon specifically didn't contribute – literature, in general, makes a point of noting what did happen, not what didn't. I'm restoring the old version. —Anonymous Dissident^Talk 08:18, 15 September 2009 (UTC)

Anonymous Dissident, you don't seem to get simple facts in scientific writing: The burden of eveidence is on the one who make an argument and not on the one who say that it's not accepted unless proved otherwise. The work of Ne'eman is mentioned and the notification that he didn't took part in the subsequent proposal of the QM is redundant at the least. So, provide source if you want to include this pointless statement.--Gilisa (talk) 08:24, 15 September 2009 (UTC)

Your argument makes no sense: if it's redundant, that implies it's already a given. If it's already a given, why should we source it? It either needs a source or it's redundant, not both. —Anonymous Dissident^Talk 08:35, 15 September 2009 (UTC)

My argument make strong sense, stop joking please. You don't seem to understand simple thing: It's pointless because there is no argument in the article he proposed the QM itself. I think it's pointless and hence delete it. I said that if you think it isn't-source it. I'm against this statement unless it's supported by source (even if it would still remain pointless by me).--Gilisa (talk) 08:40, 15 September 2009 (UTC)

I'm not joking. Re-read what I said. Something cannot be both pointless and requiring of a source. —Anonymous Dissident^Talk 09:18, 15 September 2009 (UTC)

Oh yes it can. It is pointless as I see it, for some reason it's probably not for you-so please provide source. --Gilisa (talk) 09:29, 15 September 2009 (UTC)

Please see the new wording, now it makes it clear that there is no intention to argue that Ne'eman suggested the QM itself (and it's not sure at all btw) and there is absolutly no need to explicitly indiacte it. For now let it stay like this. --Gilisa (talk) 09:51, 15 September 2009 (UTC)