Talk:List of baryons

This is the discussion/talk page for: List of baryons.

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Let's bring this to Featured List/Article status

Let's get to work folks.Headbomb (talk) 17:47, 20 April 2008 (UTC)

List of suggested improvements that remains to be done (or to be thrown away)

• Add references for section on Isospin and quark content. Headbomb
• Decide what stays here and what goes on the baryon page. Headbomb
• Possible diagram update/removal. (Diagrams were integrated in overview text). Headbomb
• List the remainder of the baryons you can make from six quarks, possibly excluding the t-quark because they do not hadronize (Did not list baryons containing t quarks). Headbomb
• Add some well-known resonances. Wing gundam

• (Decided to remove the resonances from here and expand the Sigma, Xi... pages to contain them instead. [[::User:Headbomb|Headbomb]] ([[::User talk:Headbomb|talk]] · [[::Special:Contributions/Headbomb|contribs]]) 02:58, 23 April 2008 (UTC))

• List exotic baryons. Headbomb
• Find decay mode references for the Delta(1232)s. (PDG reference contains them, albeit in a cryptic way.) Headbomb

List Progress Overview

Bold means currently not in the list. Blanks could be particles, or could be forbidden states. x are forbidden states. See Rules for making baryons - Take 3 down this page.

Particles and Isospins

Makeup	Isospin 0	Isospin 1/2	Isospin 1	Isospin 3/2
uuu	x	x	x	Delta++
uud	x	Proton	x	Delta+
uus	x	x	Sigma+	x
uuc	x	x	Sigma C++	x
uub	x	x	Sigma B+	x
uut	x	x	Sigma T++	x
udd	x	Neutron	x	Delta0
uds	Lambda0	x	Sigma0	x
udc	Lamba C+	x	Sigma C+	x
udb	Lambda B0	x	Sigma B0	x
udt	Lambda T+	x	Sigma T+	x
uss	x	Xi0	x	x
usc	x	Xi C+	x	x
usb	x	Xi B0	x	x
ust	x	Xi T+	x	x
ucc	x	Xi CC++	x	x
ucb	x	Xi CB+	x	x
uct	x	Xi CT++	x	x
ubb	x	Xi BB0	x	x
ubt	x	Xi BT+	x	x
utt	x	Xi TT++	x	x
ddd	x	x	x	Delta0
dds	x	x	Sigma-	x
ddc	x	x	Sigma C0	x
ddb	x	x	Sigma B-	x
ddt	x	x	Sigma T0	x
dss	x	Xi-	x	x
dsc	x	Xi C0	x	x
dsb	x	Xi B-	x	x
dst	x	Xi T0	x	x
dcc	x	Xi CC+	x	x
dcb	x	Xi CB0	x	x
dct	x	Xi CT+	x	x
dbb	x	Xi BB-	x	x
dbt	x	X BT0	x	x
dtt	x	Xi TT+	x	x
sss	Omega-	x	x	x
ssc	Omega C0	x	x	x
ssb	Omega B-	x	x	x
sst	Omega T0	x	x	x
scc	Omega CC+	x	x	x
scb	Omega CB0	x	x	x
sct	Omega CT+	x	x	x
sbb	Omega BB-	x	x	x
sbt	Omega BT0	x	x	x
stt	Omega TT+	x	x	x
ccc	Omega CCC++	x	x	x
ccb	Omega CCB+	x	x	x
cct	Omega CCT++	x	x	x
cbb	Omega CBB0	x	x	x
cbt	Omega CBT+	x	x	x
ctt	Omega CTT++	x	x	x
bbb	Omega BBB-	x	x	x
bbt	Omega BBT0	x	x	x
btt	Omega BTT+	x	x	x
ttt	Omega TTT++	x	x	x

Created by Headbomb (talk) 17:39, 21 April 2008 (UTC)
Last updated by [[::User:Headbomb|Headbomb]] ([[::User talk:Headbomb|talk]] · [[::Special:Contributions/Headbomb|contribs]]) 00:58, 27 April 2008 (UTC)

Rules for making baryons

I'm kinda confused about how baryons are made up. All I can find is that baryons are made of up three quarks. Since there are 6 kinds of quarks, shouldn't there be 6^3=729 distinct baryons (going by quark composition)? Not only that, but the delta+ and the proton have the same quark make-up, the only difference are the different spin states. Wouldn't this mean that there are even more distinct particles since we have to keep tract of the spin alignments of the baryons with u and d quarks? Headbomb 20:43, 21 March 2008 (UTC)

Don't you mean 6^3=216 baryons? I don't know the answer. SkyLined (talk) 20:50, 21 March 2008 (UTC)

Alright I've looked into this. It seems (from what I can gather) that I was on the right track. It looks like baryons are made from 3 quarks, any quarks. Since there are 6 different quarks, then we have 6^3 combinations of 3 quarks. However, from the Delta+ and the proton, each with quark composition u/u/d, it looks like the spin orientation have to be taken into account. Since each quark can be in +1/2 or -1/2 isospin state, then we have 12 different quarks/quarkstates possible for each of the three quarks, which gives us 12^3 different combinations of three quarks. If we remove the degeneracies (such as ssd (3/2),sds(3/2),dss(3/2)), then we have 364 (12+11+10...+11+10+9...+10+9+8+...3+2+1+2+1+1) distinct combination of quarks/quarkstates.

Now I'm not sure of this, but I think that it is the modulus of the spin that is important, so particles with spin -3/2 and -1/2 really are the same than the particles with spin 3/2 and spin 1/2. Removing these degeneracies leaves us with half the particles, and thus there are 182 distinct baryons that can be made from three quarks.

Did I understand it correctly? Headbomb 21:41, 22 March 2008 (UTC)

It's far more complicated than that. Saying that the quark content of a baryon is xyz is shorthand that hides a lot of detail. For the uds system, there are three orthonormal states: ½(usd - sud + dsu - sdu), 1/sqrt(6)(uds - usd - dus + sud - sdu + dsu), and 1/sqrt(12)(usd - sud + sdu - dsu + 2dus - 2uds). Counting hadrons is most easily done with SU(n) multiplets, but I don't fully understand them, so I can't explain it. In addition there are all the excited states as well. Finally, it's a bit academic to count the top quark in these calculations—it will decay to W+b long before it has a chance to hadronize.Mjamja (talk) 13:40, 18 April 2008 (UTC)

Yes, I've read a bit on the topic since, and the update by Wing Gundam help me understand things better. Isospin is what matters when differentiating particles of the same quark makeup. Now to understand what the hell Isospin is...

In any cases, for baryons made of 3 quarks of 6 flavors, there are (6+5+...)+(5+4+3+...)+(2+1)+(1)=56 distinct quark makeup. And while counting the t-quark baryons may be academic, I'm trying to understand the rules for making baryons are, rather than what baryons may be found in nature.

Also would be interesting if someone updated the list of baryons to take into account all the possibilities, with placeholders for the undiscovered particles Headbomb 22:12, 22 March 2008 (UTC)

I don't think it's scientific to declare a baryon before one is actually observed in an acclerator... Wing gundam (talk) 17:25, 17 April 2008 (UTC)

Are you saying is that we should not write about anything that is predicted/expected/suspected to exist but which has not been proven through laboratory testing? That doesn't sound very scientific to me ;) -- SkyLined (talk) 08:08, 24 April 2008 (UTC)

I agree in a certain way to wing gundam: Probably we should have different tables for observed and predicted (and not yet observed) SM baryons.. Tatonzolo (talk) 12:41, 24 April 2008 (UTC)

You are right in that it should be clear which particles have been proven to exist and which are predicted to exist, but have not been seen. Having two tables is a valid option, but putting everything into one table and marking them in some way is a valid alternative. I think the choice between these two options is a trade off between making it clear which baryons are similar (=one table, putting simililar baryons close together) and making it clear which baryons have been proven to exist (=two tables, seperating proven and non-proven baryons). I prefer one table, with a clear marker to indicate which particles are proven and which are not, but I have no argument other than personal preference. If we go with that option, we should put a remark ABOVE the table, so people know what to expect, rather than as a footer (which may not get read). -- SkyLined (talk) 14:27, 24 April 2008 (UTC)

concerning the clarity of the Baryon table I would suggest to make some "multilines" for the names, having Delta repeated lots of times is not beatiful, and possibly the p/n/n+ and n/n/N0 notations are quite unused... this was on the aesthetical side.. on practical side it would be useful to group the Baryons "a-la PDG" grouping them by flavour quantum numbers.. The mass scale for the Baryons would be mmore understandable to the less experts and the resonances would be better fitted... Tatonzolo (talk) 15:13, 24 April 2008 (UTC)

I think dividing them into unobserved and observed tables would clutter up the page and we'd lose part of the benefits of grouping particles together in the table. Also unobserved particles have daggers next to names to indicate exactly that, and have their masses, decay, lifetimes, and references missing. We could always add (unobserved) next to their names, I guess (removing daggers). Or we could add the move dagger note at the top of the table, (this option gets my vote for now).

Also I've list the p/p+/N+ because even though they are rarely used, they are still used. Perhaps we could add a note that p and n are the most commonly used symbols, with p+ and n0 trailing behind. As a side note, I've used p+ and n0 everywhere to indicate the charge in decays and whatnot, so it's easier to see charge conservation.[[::User:Headbomb|Headbomb]] ([[::User talk:Headbomb|talk]] · [[::Special:Contributions/Headbomb|contribs]]) 16:40, 24 April 2008 (UTC)

Take 3

Alright. I think I have it.

u and d quarks each carry isospin 1/2. This is why isospin can be either 3/2 (3 aligned u and/or d quarks), 1 (2 aligned u and/or d quarks), 1/2 (2 aligned u with one unaligned d, 2 aligned d with one unaligned u, or 1 u or d quarks) or 0 (unaligned u and d quarks, or 0 u or d quarks). Three unaligned u or three unaligned d is forbidden by Pauli, and so is two unaligned u or two unaligned d.

Isospin 3/2 baryons are the 4 Deltas (uuu, uud, udd, ddd) Isopin 1 baryons are the 12 Sigmas (uus, uuc, uub, uut, uds, udc, udb, udt, dds, ddc, ddb, ddt) Isospin 1/2 baryons are the two nucleons (uud, udd), and the 20 Xis (uss, usc, usb, ust, ucc, ucb, uct, ubb, ubt, utt, dss, dsc, dsb, dst, dcc, dcb, dct, dbb, dbt, dtt). Isospin 0 baryons are the Lambda (uds, udc, udb, udt) and the 20 Omega (sss, ssc, ssb, sst, scc, scb, sct, sbb, sbt, stt, ccc, ccb, cct, cbb, cbt, ctt, bbb, bbt, btt, ttt).

And thus there are 62 triquark baryons. [[::User:Headbomb|Headbomb]] ([[::User talk:Headbomb|talk]] · [[::Special:Contributions/Headbomb|contribs]]) 00:53, 27 April 2008 (UTC)

wrong. again. (don't mean to be harsh, but...). isospin is a number unique to baryons. however, the biggest mistake i notice is that you're listing baryons containing top quarks, which don't even exist! (see the note i left on your talk). There are no true rules for 'baryon making', whatever the hell that even is. The list, at this moment, is actually complete, provided no-one attempts to stuff it with theorical baryons, some of which may not exist. Really, the only thing this article needs is to lose some dead fat.
For example, the section "Relation between isospin and up and down quark content" is completely irrelevent to the present subject matter, by which i mean to say an explication of the fine details of isospin has no place in a list of baryons. On a side note, yet equally valid point, this section is full of gross errors in its basic understanding of particle physics, making elementary mistakes of comprehension in its explanation of isospin. This is meaningless, however, as it already does not belong on a list. The section currently labeled overview suffices to perform its function of acting as a legend, and, in truth, i think it looked much better before it was even split from the introductory paragraph. This is, after all, a LIST.Wing gundam (talk) 02:16, 29 April 2008 (UTC)

Well, I know that PDG lists that u quarks have isospin 1/2 and that d quarks have isospin -1/2, so isospin cannot be unique to baryons. Especially considering that the pi mesons form an isospin triplet. As for t quarks, I've sort of giving them a "magnetic monopole" treatment (see my talk page). I'm not opposed to not listing them, but it would be nice to know where they would fit, were they to have a bigger lifetime.

And there must be a rule for what baryons can exist, else they wouldn't show patterns such as [1]. Stuff like SU(3)xSU(2)xU(1) or SU(6) represents something and obey some rules. I'm trying to figure what the hell those rules are, and there are no books out there that seem to care to explain things to people that don't know Lie algebra, and the books on Lie algebra aren't written to be understood. At least tell me where I'm wrong, or how I'm wrong. All I know is with the rules I gave, I can reproduce every baryon diagram I encountered, and I can "predict" every baryon listed in the PDG. I can think of no reason why
Ξ⁻
_bb (observed) could exist and that
Ξ⁰
_cb(unobserved) could not. [[::User:Headbomb|Headbomb]] ([[::User talk:Headbomb|talk]] · [[::Special:Contributions/Headbomb|contribs]]) 15:11, 29 April 2008 (UTC)

Perhaps I can offer a historical explanation of Isospin to help in general understanding. Mesons and Baryons occur in multiplets. Members of the same multiplet have similar masses and differ in charge number by unit steps. Also the interactions of different members of a multiplet do not depend strongly on their charge. For these reasons each member of a given multiplet can be regarded as a different charge state of a single particle which has an extra degree of freedom in an internal space -- isospin space. The number of possible orientations of a particle in isospin space is 2I + 1. Thus the isospin quntum number of a particle may be determined simply by finding out how in how many charge states it can exist.--Vectorboson (talk) 20:30, 1 May 2008 (UTC)

Also, on the issue of rules for a baryon to exist. The first rule is that it will exist unless there is a reason it cannot. In the case of a baryon containing the top quark, calculations have been done to estimate the time it takes for a baryon to form and the result is that it takes longer for a baryon to form than it takes for the top quark to decay (about 10 to -24 seconds). --Vectorboson (talk) 20:30, 1 May 2008 (UTC)

Old rules vs. new rules

[copied from Vectorboson's talk page]

With my old rules, I could make every baryons out there with no extra baryons. The rules were quarks of the same flavor must have their isospin aligned, and quarks of different flavor can, but need not, have their isospin aligned. See Talk:List of baryons#List Progress Overview for the list of particles and their corresponding isospin values it gave me.

Now if I go with the PDG rules; that I and Iz are additive numbers and that I = 1⁄2 for u and d quarks and that Iz = 1⁄2 for u and −1⁄2 for d, then I can't account for nucleons (can't get isospin 1⁄2 with three u or d quarks, and Lambda's (can't get isospin 0 with a u and d quark).

So what am I missing? [[::User:Headbomb|Headbomb]] ([[::User talk:Headbomb|talk]] · [[::Special:Contributions/Headbomb|contribs]]) 00:20, 4 May 2008 (UTC)

First, I-spin is NOT additive, I_z IS additive-- so forget about I-spin for a minute and concentrate on I_z. When constructing composite particles, I_z is the additive quantum number. A proton has two up quarks and one down quark -- the I_z values add to 1/2. The neutron has two down quarks and one up quark-- the I_z values add to -1/2. I-spin doesn't have a direction in real space, so I-spin CANNOT "align" as can spin.

Lambda's have one up and one down quark (total I_z = 0) plus another quark with I_z = 0 -- total lambda I_z then = 0.

Did that help?--Vectorboson (talk) 01:01, 4 May 2008 (UTC)

Resonance

"This is not always the case, as with Ξ⁰_c (J=1/2) and Ξ⁰_c (J=1/2), where the J=1/2 state is marked by Ξ′⁰_c, the prime in this case also indicating a resonance, but of the same spin."

Is that sentence really what is meant? Or is this better?

"This is not always the case, as with
Ξ⁰
_c (J=1/2) and
Ξ^∗0
_c (J=1/2), where the prime indicates a resonance, but of the same spin."Headbomb (talk) 04:31, 20 April 2008 (UTC)

I changed the sentence to what I felt was more accurate.Headbomb (talk) 17:25, 20 April 2008 (UTC)

I have removed the resonances from the list, and expanded the Sigma baryon,Xi baryon... pages to contain them instead.[[::User:Headbomb|Headbomb]] ([[::User talk:Headbomb|talk]] · [[::Special:Contributions/Headbomb|contribs]]) 03:00, 23 April 2008 (UTC)

The resonances you removed represented unique particles of the 10+8+8'+4 20-plet, with the same difference as Delta+'s and protons, which is why they were explicitly left, and identified with a prime.Wing gundam (talk) 02:23, 29 April 2008 (UTC)

If you remember what they were, you can find them in the Sigma baryon, Xi baryons, etc... pages to save you the trouble of retyping all the code.[[::User:Headbomb|Headbomb]] ([[::User talk:Headbomb|talk]] · [[::Special:Contributions/Headbomb|contribs]]) 04:14, 29 April 2008 (UTC)

Isospin, decay mode, resonance listings

I'm preparing to add a separate column for isospin, if there are no objections. I'm also going to list the mass after every particle's symbol which requires it, per PDG guidelines. I also strongly recommend against listing high energy resonances of baryons, say, for the Sigma0 J=1/2 and Sigma0 J=3/2, as in fact there exist numerous other values of J, even if they do not exist in any pyramid-like table. 68.10.32.199 (talk) 17:19, 17 April 2008 (UTC)

I suggest we include all baryons with 3 or 4 star status in the PDG, since this is the definitive source for information like this. That would mean lots of Ns, Δs, Λs and Σs, but none of the double and triple charm and bottom states that have not been observed.Mjamja (talk) 13:40, 18 April 2008 (UTC)

You understand that the majority of these are isomers, right? i.e. theyre not actual "distinct" baryons. though difficult to describe, they're basically energized variants of their ground states. Don't think of these resonances as separate baryons; rather, imagine them as 'energized variations' of a representative particle.
If we are attempting to make a list of baryons, which has the potential to become grossly over-complicated by including minor variations of almost every entry, and terribly confusing to anyone who isn't an expert on particle physics, I think it would be better to include only the aforementioned representative particle, although a few exceptions are necessary:
From the article, "Recursively, for each baryon group (Nucleon, Delta, Sigma, etc) and for each possible quark content structure possible within the group, data for the ground resonance state of the arrangement has been included. ... Currently, certain other well known resonances, namely those populating the decuplet of the primary SU(3) and the 20-plets of the SU(4) groups, are included below."Wing gundam (talk) 07:02, 19 April 2008 (UTC)

Oops forgot to log in. I'm also going to add a † marker and a note below the table to denote particles not yet observed. Wing gundam (talk) 17:22, 17 April 2008 (UTC)

According to Isospin#SU(2), "... isospin is described by two numbers, I, the total isospin, and I₃, the component of the spin vector in a given direction. The proton and neutron both have I=1/2, as they belong to the doublet. The proton has I₃=+1/2 or 'isospin-up' and the neutron has I₃=−1/2 or 'isospin-down'.". Please make clear in each instance in the article where you mention isospin whether you are talking about the total isospin or the component. JRSpriggs (talk) 14:54, 29 April 2008 (UTC)

It is always the modulus of the isospin (I) we're talking about, except when isospin projection are mentionned (I_z), but I guess that could be clarified.[[::User:Headbomb|Headbomb]] ([[::User talk:Headbomb|talk]] · [[::Special:Contributions/Headbomb|contribs]]) 15:06, 29 April 2008 (UTC)

Diagram Updates

I think it would be a good idea if we could fit something like theses diagram somewhere in the article

http://www.fnal.gov/pub/inquiring/physics/discoveries/images/Baryon%20Chart_MR.jpg
http://www.regenerating-universe.org/images/Baryon.gif
Headbomb (talk) 18:03, 20 April 2008 (UTC)

On second thought, the more I look at them, the less I see a need for them. They already are in the baryon article.Headbomb (talk) 07:02, 21 April 2008 (UTC)