Talk:List of mesons

Comments

If you want to get really anal about CP-violating terms, they appear for all mesons, not just kaons. Also, the standard mixing of the neutral pion and the eta is broken by quark mass terms. -- Xerxes 17:41, 2005 August 4 (UTC)

Good point. It's important historically for the kaons, though. I'll think about how to note this. -- SCZenz 18:32, 4 August 2005 (UTC)

Wait a minute... The CP-violating terms should only appear in the states of flavored neutral mesons, i.e. those that can mix with their antiparticles via box diagrams. Any meason has direct CP violation in its decays, also, but that's not too relevant to the table. So I just need notes for K, D, B,and B_s. Am I right about this? -- SCZenz 16:52, 5 August 2005 (UTC)

Yeah, that's right. Just the neutral mesons. -- Xerxes 19:08, 2005 August 5 (UTC)

And one doesn't talk about D-longs or B-shorts because the extra-long lifetime for one weak eigenstate is unique to kaons. Thus for the other neutrals, only the strong eigenstates are considered particles, and those are exactly as listed. I have put a brief note at the end of the kaon notes clarifying this point, and now think it's good as is. -- SCZenz 20:06, 5 August 2005 (UTC)

Table

Is there any way to make the table smaller? 24.126.199.129 03:37, 24 August 2006 (UTC)

Yeah, the notes could be numbered and made into footnotes. Maybe I should do that. -- SCZenz 03:38, 24 August 2006 (UTC)

References mistake

I don't have the book in front of me right now, but the Griffiths E&M book listed is surely a mistake? I used the book in undergraduate and don't recall a list of mesons. Perhaps one means his book on elementary particles? -Joshua Davis 22:29, 12 January 2007 (UTC)

Eta Prime Wavefunction

I got D.B. Lichtenberg's Unitary Symmetry and Elementary Particles (2nd Editition) before me and he lists the Eta Prime wave function as ${\frac {1}{2}}(u{\bar {u}}+d{\bar {d}}+s{\bar {s}}+c{\bar {c}})$ instead of ${\frac {1}{\sqrt {3}}}(u{\bar {u}}+d{\bar {d}}+s{\bar {s}})$. Who's right? Headbomb (talk) 21:54, 3 April 2008 (UTC)

The PDG lists the eta-prime among the "light unflavored mesons" and suggests its quark content is a combination of $(u{\bar {u}}+d{\bar {d}}+s{\bar {s}})$. The same source that I suggested is good for the baryon page is good for this page as well.
http://www.hep.phy.cam.ac.uk/~thomson/partIIIparticles/handouts/Handout8_2007.pdf
It lists the eta-prime as ${\frac {1}{\sqrt {3}}}(u{\bar {u}}+d{\bar {d}}+s{\bar {s}})$--Vectorboson (talk) 14:12, 9 May 2008 (UTC)

Eta prime's strangeness

In the table it's written that Eta prime's strangeness is 1; but in mesons of spin 0's nonet graph and according to listed eigenfuction ($+s{\bar {s}}$) its strangeness should be 0. I'm editing the table. M. Casati 90.133.30.97 (talk) 09:12, 8 June 2008 (UTC)

Import from list of baryons

I've imported the stuff from the list of baryons so we can use it as the skeleton of the list of mesons. Many sections need to be re-written with mesons in mind. Headbomb (ταλκ · κοντριβς) 04:25, 12 June 2008 (UTC)

Comments on Kaons notes and on Eta prime

Too much technical gibber and not enough thought. There need to be four K mesons, two neutrally charged and one + and one -, all with approximate mass 892.2 Mev corresponding to Strangeness +1 and Strangeness -1 multiplied by isospin +1/2 and -1/2. Elsewhere in Wickipedia you have the correct hexagonal diagram for vector mesons --- check it up. More staggering is the omission of the omega0 vector meson of mass783.4 Mev. If you add these it will make your table of vector mesons compatible with your diagrams that appear elsewhere.

Also in your table of pseudoscalar mesons, for goodness sake don't call it an eta prime meson (it is nothing to do with the actual eta meson, and there is too much confusion). Sensible people call this the X meson and it has zero charge.

- IP 58.110.22.167

Do you have refs for all this? I also know the PDG calls it the eta prime meson, I don't see why they would get something like this wrong. Headbomb {ταλκ – WP Physics: PotW} 15:40, 25 June 2008 (UTC)

Vector Mesons

Can someone with access to the information add the rest of the uds vector mesons? I can't seem to find, for instance, the mass of K* anywhere I look. Aaronzimmerman (talk) 18:04, 4 August 2008 (UTC)

Completing the tables

I'm currently expanding the List of mesons to be something similar to the List of baryons. Right now I'm identifying the vector mesons equivalent of the pseudoscalar mesons and I'm having some trouble. So far I've got:

Pseudoscalar (anti)	PS ref	Vector (anti)	Vector ref
π+ (π−)	Particle listings – π±	ρ+ (ρ−)	Particle listings – ρ
π+ (self)	Particle listings – π0	ρ+ (Self)	Particle listings – ρ
η (Self)	Particle listings – η	ω(782) (self)	Particle listings – ω (782)
η′(958) (self)	Particle listings – η′	φ (self)	Particle listings – ϕ
ηc(1S) (self)	Particle listings – η c	J/ψ (self)	Particle listings – J/Ψ
ηb(1S) (self)	Particle listings – η b	Υ(1S) (self)	Particle listings – ϒ
K+ (K−)	Particle listings – K±	K*+ (K*−)	Particle listings – K∗ (892)
K0 (Anti-K0)	Particle listings – K0	K0 (Anti-K0)	Particle listings – K∗ (892)
KS0 (self)	Particle listings – K0 S	K*S0 (self)	??
KL0 (self)	Particle listings – K0 L	K*L0 (self)	??
D+ (D−)	Particle listings – D±	D*+ (D*−)	Particle listings – D∗± (2010)
D0 (Anti-D0)	Particle listings – D0	D*0 (Anti-D*0)	Particle listings – D∗0 (2007)
Ds+ (Ds−)	Particle listings – D± s	D*s+ (D*s−)	Particle listings – D∗± s
B+ (B−)	Particle listings – B±	B*+ (B*−)	Particle listings – B∗
B0 (Anti-B0)	Particle listings – B0	B*0 (Anti-B*0)	Particle listings – B∗
Bs0 (Anti-Bs0)	Particle listings – B0 s	B*s0 (Anti-B*s0)	Particle listings – B∗ s
Bc+ (Bc−)	Particle listings – B± c	B*c+ (Anti-B*c−)	Undiscovered?

Now with the italicized entries, I'm assuming that putting stars on the pseudoscalar meson yields the vector meson. I could be wrong about that. I'm especially unsure of the starred K-short and K-long. Also, I'm browsing the PDG listings and I'm afraid I just don't really know what I'm looking for. So if you could find the reference and place it in the above table for me, that would be very helpful. Just place the raw link in the appropriate place in the table and I'll do the rest.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 05:31, 13 November 2008 (UTC)

I think I've found some of the things I were looking for. If I'm wrong about them, just write over what's there or otherwise let me know.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 08:28, 13 November 2008 (UTC)

Also, how far out in the left field would I be if I were to list things such as
B⁰
_L/
B⁰
_S, and
D⁰
_L/
D⁰
_S? Or are the K_S/L just considered special because of arbitrary reasons such as their big lifetimes? Headbomb {^ταλκ_{κοντριβς} – WP Physics} 15:01, 17 November 2008 (UTC)

There's no such thing as anything like the K-long and K-short for any other cases, including the "starred" case. For the K, these (almost) CP-eigenstates are physically distinguishable, because they have very different decay times. Without this unique phenomenological behavior, caused by the very small difference between the kaon mass and the mass of three pions, the CP eigenstates don't really act like separate particles and nobody talks about them as such. -- SCZenz (talk) 15:50, 17 November 2008 (UTC)

Alright, good enough for me. Thanks.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 17:18, 17 November 2008 (UTC)

Charged pion CP values.

The rho has J^PC = 1 ⁻⁻ for all charges, but the pion J^PC = 0 ⁻⁺ for the neutral and J^PC = 1 ⁻ for the charged versions. Why doesn't the charged pion have a C parity value defined? Is this an ommision from the PDG? Headbomb {^ταλκ_{κοντριβς} – WP Physics} 08:46, 13 November 2008 (UTC)

The listed C value is the eigenvalue for the particle under the charge-conjugation operator, if the particle is an eigenstate of the operator. That's only possible for particles that are their own antiparticles. C|π⁺> = |π^->, so neither one has a defined C parity. -- SCZenz (talk) 13:55, 17 November 2008 (UTC)

So basically the charged rhos are J^P=1⁻ and the neutral rho is J^P=⁻⁻, but they are both written as J^PC=⁻⁻, as the PDG assumes that their typical reader will know that it is clear that the C value is only for the neutral rho? I'll edit accordingly. Thanks. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 14:55, 17 November 2008 (UTC)

Yes, if they were listed separately, the charged rho would say J^P=1⁻ while the neutral row would say J^PC=1⁻⁻. -- SCZenz (talk) 12:07, 18 November 2008 (UTC)

Lifetimes

Many of the particles didn't have their lifetimes listed, so I "extracted them" using

$\tau ={\frac {h}{2\pi \Gamma }}$

And uncertainties with

${\Delta \tau }={\frac {h}{2\pi \Gamma ^{2}}}\Delta \Gamma$

as the PDG did for Brownian 74 in [1]. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 17:26, 17 November 2008 (UTC)

Notes on neutral kaons

The section Notes on neutral kaons has the following statement.

• Due to neutral kaon mixing, the
  K⁰
  _S and
  K⁰
  _L are not eigenstates of strangeness. However, they are eigenstates of the weak force, which determines how they decay, so these are the particles with definite lifetime.

In my opinion this statement may lead a reader into believing that the reason for the short and long kaons different lifetimes is the different ways they interact through weak force. We should make the role played by CP symmetry more clear.

I don't know how you infer that from the text, but I agree it could be make clearer that CP violation plays a part here. I would also consider adding the analogous
B⁰
_S/
B⁰
_L,
D⁰
_S/
T⁰
_L,
T⁰
_S/
T⁰
_L states, and put those in context of the BaBar/Belle experiments for exemple, and then to discuss why people do not usually speak of
B⁰
_S/
B⁰
_L states.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 00:47, 17 February 2009 (UTC)

Charges, Spin, And Baryon Numbers Not Provided. Quark Content Confusing

The article mentions that some mesons can be charged, notes that charge is represented by the symbol Q, but provides no charge values for the particles, nor any way to derive charge values from other provided values.

A similar situation exists for spin (as opposed to isospin) and baryon numbers. I have a feeling that spin can be calculated from total angular momentum and that baryon numbers are all zero due to quark/anti-quark combos. But not being a subject matter expert, I don't know that for certain and I'm left wondering why Charge, Spin, and Baryon Numbers are described to be important qualities, but no values for them are given.

Also the Quark Content is confusing to non-experts. For example, it's not at all clear what it means to divide a group of quarks by the square root of six. An explanatory note on this would be welcome.—Preceding unsigned comment added by 173.59.61.57 (talk) 14:57, 3 September 2009 (UTC)

Charges are part of the particles' names, and are written as superscripts. All pseudoscalar have spin zero and all vectors have spin one, and this spin is identically equal to the total angular momentum given. The baryon number of all mesons is, indeed, zero. The square roots in the quark content are just normalization factors. MuDavid (talk) 14:58, 8 June 2010 (UTC)

List is massively incomplete

The article starts with "This list is of all known and predicted mesons." It is NOT. It misses most known mesons. Have a look at Quarkonium for example to find 23 observed mesons and more predicted ones that are not on the list, and that's only the tip of the iceberg. The total number of known and predicted mesons is about ten times as large as this list. Mesons missing from the list include f0(600), f0(980), a0(980), h1(1170), b1(1235), a1(1260), f2(1270), f1(1285), eta(1295), pi(1300), a2(1320), f0(1370), pi1(1400), eta(1405), f1(1420), omega(1420), a0(1450), rho(1450), eta(1475), f0(1500), f'2(1525), pi1(1600), eta2(1645), omega(1650), omega3(1670), pi2(1670), phi(1680), rho3(1690), rho(1700), f0(1710), pi(1800), phi3(1850), pi2(1880), f2(1950), f2(2010), a4(2040), f4(2050), phi(2170), f2(2300), f2(2340) - and that's just the missing ones that only involve up and down quarks, the total missing list is at least six times this length. Here's a more complete list: http://pdg.lbl.gov/2010/tables/rpp2010-qtab-mesons.pdf, but even that misses most of the mesons listed in quarkonium, so presumably others as well.Mollwollfumble (talk) 18:01, 5 April 2011 (UTC)

I've started the project a while ago, but never bothered finishing up with the scalar mesons and the pseudovector mesons. I've updated the hatnote to read "This list is of all known and predicted pseudoscalar and vector mesons." Headbomb {talk / contribs / physics / books} 19:10, 5 April 2011 (UTC)

How do you categorise mesons with J = 2,3,4,5,6, + and -. Tensor mesons? Do you now wish that you'd split the tables up by quark content rather than by total angular momentum? f0(2200) is listed by Nakamura as J^PC (2++ or 4++); X(3872), although considered well established, is listed as (??+) Mollwollfumble (talk) 21:29, 6 April 2011 (UTC)

What is missing are the scalar and pseudovector mesons. Anything with J = 2 or more (like the tensor J^P = 2⁺) is a resonance of a lower state so I don't really see a need for their inclusion. Organizing by quark content is problematic, at least with the current naming scheme, so is not very viable either. Headbomb {talk / contribs / physics / books} 21:57, 6 April 2011 (UTC)

"is a resonance of a lower state so I don't really see a need for their inclusion." OK. I do. I've put together a summary table based on http://pdg.lbl.gov/2010/tables/rpp2010-qtab-mesons.pdf. I won't change anything else you have there. Mollwollfumble (talk) 10:45, 7 April 2011 (UTC)

Remove the table

The table says "Because this table was initially derived from published results and many of those results were preliminary, as many as 64 of the mesons in the following table may not exist or have the wrong mass or quantum numbers."

How is this table appropriate for an encyclopedia entry given this comment? — Preceding unsigned comment added by 24.22.157.155 (talk) 01:30, 13 February 2017 (UTC)

Module:Particles

This article currently has a post‐expand include size of 1,855,886 bytes. The limit is 2,097,152 bytes—if that is ever reached, templates will fail. If that happens, review my edits to fix List of baryons and see Talk:List of baryons#Templates. If wanted, I could similarly improve the efficiency of this page using Module:Particles. Johnuniq (talk) 06:24, 19 March 2018 (UTC)

"templates will fail" REALLY? Maybe you should discuss it on phabricator. 109.252.171.205 (talk) 20:58, 2 July 2020 (UTC)

41.66.181.77 (talk) 18:48, 13 April 2021 (UTC)

Errors in Meson Table (the "Meson Summary Table" at "List of Mesons")

There is errors in the table: Pi-zero hasn't got +1 charge, eta hasn't got +1 charge, roh-(zero ?)(770) hasn't got -1 charge, omega-(zero?)(782) hasn't got -1 charge, and there are more errors. — Preceding unsigned comment added by 41.66.181.77 (talk • contribs)

What are you talking about? There are no "list of muons" anywhere. Headbomb {t · c · p · b} 18:56, 13 April 2021 (UTC)