List of baryons

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This peer review discussion has been closed.
. I've listed this article for peer review because…

The list of baryon is complete (or near complete) and up to date. However I am not a particle physicist, so I cannot know for sure if my understand of some things was accurate. Not many people worked on the page, and it is hard to know if the page can be understood by people other than us. There are useful things in the talk pages and some ongoing discussion about the direction should talk in order to become a featured list.

Thanks, Headbomb (talk · contribs) 21:18, 23 April 2008 (UTC)[reply]

Overview of the PR

Only edit this to summarize the state of the PR as of now

Unresolved issues as of 2008-04-28:

• Column content

Proposal to add date discoveries and artists' rendering of baryons. Proposal to chop down particle names, Q,S,B,C columns. Proposal to chop down Q,S,B,C columns, and to not include dates and images, but to keep particle names.

• Level of expertise expected from the reader
• Pentaquarks: include or exclude?
• Uniformity of notes and foot notes.
• See also section content
• What is a "complete" list of baryons?

Headbomb wrote List of baryons#Relation between isospin and up and down quark content. Section needs to be verified and referenced.

• What do we do with the baryon diagram?

Proposal to integrate within text or to remove

Comments by Mike Peel

I'll try to look into the article in more depth when I can (and lend a hand on the page itself), but here are some comments from a quick scan through it before I go to bed:

• "partial list": why is it partial? Just incomplete, or with criteria for inclusion set?
• I'd move anything vital from the "Overview" into the introduction, and then move the Overview section down to below the list and call it "Explanation" or something along those lines. The section seems out of place as it currently stands.
• I'd rename the "List of baryons" section to just "Baryons"; the same goes for "List of exotic baryons (pentaquarks)" to either "Exotic baryons" or "Pentaquarks".
• Columns for the date and location of the discoveries would be useful. Possibly also a column with images (at least some of the baryon pages have artist's impressions); see List of moons for an example.
• Missing values within the table should either be filled in, or marked as "unknown" where necessary.
• I'd stick to a single type of footnotes: at present you use [1] for references, as well as [a] and symbols for footnotes-in-sections. Could they not all use the standard footnotes system, with the "References" section renamed to "Notes and references"? The footnote in the exotic baryons section could probably be moved into an introduction sentence to that section, and possibly expanded upon.
• I'd integrate the baryon diagrams into the text-y bits of the article (e.g. one at the top, one in the overview/explanation section); having them in their own section looks odd.
• Do you need the "See also" links? Aren't most of them in the navigation box at the bottom?
• The "Baryon discoveries in the 2000s" links section should either be integrated into the references, or removed. Wikipedia doesn't have links sections.
• Your references need some work on their formatting. The accessdate should be of the form "accessdate=2008-04-23"; it will be automatically turned into a formatted date. The PDG references have authors and publishers, as well as journal references: these should be mentioned. The ((Cite journal)) template should probably be used instead of ((cite web)).

The article looks a lot better than it did a month ago: you've made some good progress. Keep it up! Mike Peel (talk) 22:32, 23 April 2008 (UTC)[reply]

Reply to Mike Peel

The following are explanations for why I did things the way I did. Part of the reason of why I asked for peer review was to get feedback on what I did and so there would be more than just two or three people deciding about how things should be done. If the reasons mention don't make any kind of sense, or that alternatives would be better, then don't be shy and point it out.

• Partial list: The list made quite a progress in the last month. Back then it was definitively not a complete list, but now perhaps it is. I am not a particle physicist, so I do not know if I truly did list all of the particles and therefore I didn't change the "partial" thing. What a "complete" list would be in my mind is a list that include all the fundamental states of all the baryons that can be made from any 3 quarks (u,d,c,s,t,b), and exclude the resonances. I have made a table of all the baryons I could think of in Talk:List of baryons#List Progress Overview
• Footnotes: The [a],[b],[c], etc... are table notes. The [1],[2],[3] are references. I've kept them separate on purpose so you could tell what was a reference, and what was a note, but perhaps there could be a way to merge the two together.
• Date of discoveries: That would be a nice addition yes, but one that would require a lot of work. Considering how large (sideways) the table already is, I think it would be better to expand the Timeline of particle discoveries page instead.
• I agree that the decuplet and octuplet images are in a weird location. I haven't found a way to integrate them seamlessly into the text.
• See also links are there (at least for now) for two reason 1) because I feel like people could be confused by the navbox. and 2) it highlights what pages are more related to the topic at hand.
• Baryon discoveries: They are there for now because they used to be the references for some of the particles (I replaced them with the PDG stuff). I didn't remove them because I thought perhaps they could eventually be integrated in paragraphs detailing some recent discoveries

Headbomb (talk · contribs) 02:21, 24 April 2008 (UTC)[reply]

Comments by SCZenz

If you're trying to have this reviewed by non-experts, as would be the case for featured or good article status, you should know that you will get a lot of complaints about the level of expertise required to understand the page. It will be very difficult to provide a satisfactory introduction to the idea of a baryon and their organization, and to explain the relevance of the table elements. A definite start would be to work the eightfold way diagrams into an introductory narrative. I'll look more later. -- SCZenz (talk) 22:48, 23 April 2008 (UTC)[reply]

As for the completeness of the list, this is difficult. Traditionally, one would list all ground-state combinations, and then those excited states (i.e. same quark content, but higher mass) which are interesting in some way. But I'm not sure what clear criteria one could give — I'll think about it.

Oh, and another comment: you should be much clearer for the unobserved particles about the values of the table, and where they come from. -- SCZenz (talk) 22:53, 23 April 2008 (UTC)[reply]

Reply to SCZenz

Well right now I'm mostly interested in factual accuracy, making sure that the list is what it should be, and that it follows wikipedia's standard of presentation. Values that have ^{[citation needed]} tags to them are those I have no clue about (mainly spin-parity values), and I am not two sure of the
Ω⁺⁺
_ccc and
Ω⁻
_bbb either, but I'm fairly certain they are 3/2+ because the Omega- is 3/2+. I think it was User:Wing gundam that added them. The isospin values combined with first generation quarks determine if particles are lambda, sigma, omegas or whatever so we know the isospin values of every particle (I gave an explanation in Talk:List of baryons#Rules for making baryons, but I don't know if I understood things correctly). The Q,C B, values are known from the quark content.

Comments by Mjamja

• Can we eliminate some of the columns? I believe there was already a request to eliminate the "Particle" column, which I would second. The only entries that gain from this are the proton and neutron entries, where the name isn't just the symbol. For these two cases I would suggest having the name beneath the symbols. The isospin column is redundant since the name of the particle tells you the isospin (and explicitly described above). The charge is explicitly noted in the superscript and the strangeness, charmness and bottomness are easily determined by looking at the quark content. Eliminating columns would help with some of the ugly wrapping, particularly in the masses, and may allow additional columns that are more interesting to be added.

• The mass notation is kind of irritating because it breaks in awkward places. Since these are at most four digits in front of the decimal point, can the space be eliminated?

• The ((val)) template is also frustrating, particularly because it doesn't respect significant zeros and it drops leading zeros in the uncertainties. Until these issues are fixed, I would suggest replacing it.

• The heading "Commonly decays to" is problematic for some of the heavy flavor baryons. These baryons in principle have lots of decay modes available, and the ones that are observed experimentally aren't necessarily the most common.

• Inclusion criteria: I would prefer to limit the list to baryons for which there is at least some claim to observation, but at a minimum t baryons should be excluded. Also, what about states like Ξ_c^0'? They have the same quark content as other baryons, but they're not orbitally excited states.

• I'm not sure pentaquarks belong on this page. I think it might distract from the focus on traditional baryons.

• Some of the J^P assignments can be found in http://xxx.lanl.gov/abs/hep-ph/9406359

• The Σ_b and Ξ_b should cite the CDF and D0 papers since they're not in PDG yet. As noted above, the papers don't merit their own section.

Mjamja (talk) 21:42, 24 April 2008 (UTC)[reply]

Reply to Mjamja

• Eliminating columns: Eliminating some columns could be done I suppose. I wouldn't be too sad kissing goodbye to Q,S,C,B values, but I would be against eliminated the name column though and the isospin. A list shouldn't just list the minimum amount of information that is required to deduce the rest of the useful information. "Ξ" will not scream "Isospin 1/2" to regular jim and knowledge of the Greek letters isn't universal.
• Mass/val templates: Cleanup is indeed required there. SkyLined will update the ((val)) templates eventually, but for now we should write things according to SI guidelines. ((val)) templates are only used for values such as 1.6+0.2
  −0.3 because I don't know how to get the same look for the uncertainties without using the templates.

NIST has the guidelines for formating numbers.

• Decays: The decay listed were the most common ones - I've checked. The PDG Data review gives the relative frequencies of decay modes. I haven't used a specific cutoff (such as a decay that happens 5% of the time or more was "common") though.
• 
  Ξ′⁰
  _c: My understanding of that particle is that it is an excited state, but with the same spin value than
  Ξ⁰
  _c. I gave it the shaft because it was not a ground state (at least in my understanding). Undiscovered particle are listed to indicate what remains to be discovered, and I think that by removing them we would be disminishing the value of the list.
• Pentaquarks: While their existences is far from being accepted, if pentaquarks exists they would indeed be baryons. IMO this is encyclopedic content, and gives information about the state of knowledge and understanding in particles physics. I have a hard time imagining how they would detract attention from the 3-quark baryon list, considering how small the list is and that it isn't "complete" in the same sense that the 3-quark baryon list is.
• Reference: I'll check the link you gave for the J/P values. And I don't know why you said that the Ξ
  _b isn't listed the PDG thing, because it is, and the Σ
  _b have the CDF as a reference...

I've checked the link you gave and I can't understand a thing. If you can, add citations where you can.

Headbomb (talk · contribs) 23:23, 24 April 2008 (UTC)[reply]

Most of the remaining differences are minor, and I'm happy to defer to the people actually doing the writing. A few comments:

• The Ξ_b measurements by CDF and D0 are much more reliable than the ones in the current PDG, but they are too recent to have been incorporated into PDG. I've changed the citations. I missed the reference to the CDF Σ_b, sorry about that.

• I would guess that the Ξ_b decays more often to Ξ_c+X, and wouldn't want to give the impression that ΞJ/Ψ decays are the most likely.

• The definition of "excited state" is a little tricky. Look at the multiplets on p. 3 of http://pdg.lbl.gov/2007/reviews/charmedbaryon_s833.pdf Fig. 2a shows J^P = 3/2⁺ states, while Fig. 2b shows ^P = 1/2⁺ states. There's a uud proton and a uud Δ⁺ that differ by quark spins. There's a uuu Δ⁺⁺, but no corresponding 1/2⁺ state. So the Δ⁺⁺ is the lowest mass uuu baryon, but the Δ⁺ is not the lowest mass uud baryon. It would seem strange to include Δ⁺⁺ and Δ^- but not Δ⁺ and Δ⁰. But then the same argument could be made to include the J^P = 3/2⁺ Σ^- and Ξ^-. It's not clear to me where to draw the line.

• I will try to reference some of the unobserved J^P values.

Mjamja (talk) 13:50, 25 April 2008 (UTC)[reply]

Mmmm. That excited state thing deserves closer attention. My impression was that while the Delta++ was the lowest mass uuu baryon, and that the proton was the lowest mass uud baryon (over the Delta+), they have different isospins values, and this made them "different" particles in the eyes of particles physicists. At least that's what the PDG rules gave me the impression. Sigma have isospin 1, whether they are in J^P
states 1/2+ or in state 3/2+ and thus were not considered "different".

Perhaps a mention that particles are listed in their fundamental spin states and that every particle in J^P
=1/2+ can also be found in J^P
=3/2+ would be in order? Unless of course I'm mistaken.Headbomb (talk · contribs) 14:55, 25 April 2008 (UTC)[reply]