Talk:Pentaquark

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Source of joke[edit]

The quote:

[T]here has not been a high-statistics confirmation of any of the original experiments that claimed to see the Θ+; there have been two high-statistics repeats from Jefferson Lab that have clearly shown the original positive claims in those two cases to be wrong; there have been a number of other high-statistics experiments, none of which have found any evidence for the Θ+; and all attempts to confirm the two other claimed pentaquark states have led to negative results. The conclusion that pentaquarks in general, and the Θ+, in particular, do not exist, appears compelling.

is frequently edited to read:

...in particular, do not exist, appears compelling, especially given the definitive result by Fred in 1971.

This is a joke by Dr Fred Loebinger for his third year particle physics students and the article is frequently edited. If you see the second quote - it is incorrect and could you please reverse the edit. Jamietwells (talk) 00:08, 10 November 2014 (UTC)

Comment by Gbrandt[edit]

This article claims discovery of pentaquarks, while they are still highly controversial within the scientific community. If nobody objects, I will rephrase this article to a much more conservative wording soon! gbrandt 09:27, 9 Dec 2004 (UTC)

I've rephrased it to say this. --Fwb22 18:10, 31 Jan 2005 (UTC)

"by accelerating energetic photons into liquid hydrogen" How does one accelerate a photon? Should this be "proton'?

I've rephrased it to say "by firing a high-energy photon beam in to deuterium" --Curtis95112 09:16, 3 December 2007 (UTC)

Out-of-date[edit]

I noticed that this page would appear to have been not updated in at least one respect. In the section "History", there is a statment that "More results from CLAS at Jefferson Lab are expected later in 2005". Will someone please update this?

scienceman 13:25, 22 March 2006 (UTC)

I'm not an expert in this subfield of physics, but I've updated the article to reflect what I've read in the latest papers. -- Xerxes 17:41, 22 March 2006 (UTC)

Disambig check[edit]

Howdy, I was helping handle the SVD disambiguation, and noticed this is the only article referring to the experiment/research group probably referred to in doi:10.1016/S0375-9474(01)01519-6. Can someone check the SVD page, make sure the description is coherent, and consider creating an article for the group/experiment if it is notable.

I also disambiguated the HERMES link to HERMES experiment. It matches the broad subject area, but I have no way of knowing if this is precisely what was meant. Can someone check? JackSchmidt (talk) 03:59, 31 January 2008 (UTC)

Citations[edit]

So far, this article seems accurate compared to what I have recently read about this topic. I will probably add in-line citations and maybe add some information as well. If I feel that something should be altered, I will note it on this talk page. Also, I hope no one minds if I remove the internal links that don't lead to an article ( these are the red links in the article). Ti-30X (talk) 10:21, 21 July 2009 (UTC)

Interation[edit]

Which interactions does this particles use to interact? Newone (talk) 05:02, 31 July 2009 (UTC)

Hysterical July 14, 2015 activity on LHCb announcement[edit]

It appears, given the singular, if not unsavory, runaway editorial activity of today, that the LHCb promotional machine agents will amend their preliminary results as moderating evidence accumulates and the preliminary indications are vetted and interpreted appropriately. WP should not become an instrument of unsavory science publicity wars. The issues might be referred to the Wikiproject physics group. Reasoned consensus may be reached on this page first, especially on over-publicized preliminary results. Cuzkatzimhut (talk) 00:44, 15 July 2015 (UTC)

Let's not attribute to malice what is most likely a great deal of enthusiasm by science lovers given the plastering of the potential discovery all over the news. The page has greatly improved since this morning, although claim of definite discovery had to be reined in given the non-peer reviewed status of the preprint, both here and on other quark-related articles. Headbomb {talk / contribs / physics / books} 01:35, 15 July 2015 (UTC)

Phew... no imprecations of "malice" there, yet... just institutionalized recklessness. I haven't seen conclusive contrast to hadronic molecules yet. Cuzkatzimhut (talk)

To be fair, doi:10.1103/PhysRevLett.114.132002 only says that the lattice Λ(1405); is consistant with a KN state, and write "it remains to demonstrate the connection between the finite-volume lattice eigenstates and the infinite-volume resonance found in nature." I don't think anyone would call that 'discovery'. Headbomb {talk / contribs / physics / books} 14:48, 15 July 2015 (UTC)

Statistical significance of the Pc(4380) and Pc(4450) in the 2015 LHCb result[edit]

I shall quote the paper:

... giving overall significances of 9σ and 12σ, for the lower and higher mass Pc+ states, respectively. The combined significance of two Pc+ states is 15σ.

The two Pc states are overlapping with narrow mass splitting. The model with both states is the one that fits best, so its significance is the most important. If you want to put 9σ, say it's the minimum significance of either of the particles individually, or quote all three values like the paper does. --128.141.170.28 (talk) 09:57, 15 July 2015 (UTC)

I suspect that this will be lost on those making the edits. They'll see the press release or whatever article reporting on the LHCb results, and those tend to have the number 9 in it. So they'll change it to nine. Headbomb {talk / contribs / physics / books} 13:18, 15 July 2015 (UTC)
OK, I have quoted all three significances in the article. --128.141.170.28 (talk) 14:34, 15 July 2015 (UTC)

Interpretation of the Pc(4380) and Pc(4450) as bound states of J/psi and proton[edit]

I have now twice removed the statement that these resonances resemble bound states of J/psi and proton. Please do not include personal interpretations in the article. It is misleading. The binding mechanism is unknown and untested. All we know is that J/psi and proton are the decay products. A neutron, for example, decays to a proton, an electron and an antineurtino. This does not mean it's a bound state of those things --128.141.170.28 (talk) 09:57, 15 July 2015 (UTC)

Slight confusion in opening paragraph[edit]

"As quarks have a baryon number of +1⁄3, and antiquarks of −1⁄3, it would have a total baryon number of 1, thus being classified as an exotic baryon. By contrast, regular baryons (or 'triquarks')—which also have a total baryon number of 1—consist of three quarks."

The first sentence gives the impression that "total baryon number = 1" is what makes this an "exotic baryon", but this is contradicted in the second sentence, when it is said that regular baryons also have this baryon number. 86.152.161.232 (talk) 18:00, 16 July 2015 (UTC)

Perhaps this would be better?
"As quarks have a baryon number of +1⁄3, and antiquarks of −1⁄3, the pentaquark would have a total baryon number of 1, and thus would be a baryon. Further, because it has five quarks instead of the usual three found in regular baryons, it would be classified as an exotic baryon."18.4.2.1 (talk) 20:29, 17 July 2015 (UTC)
The formal definition of a baryon is 'something that has a baryon number of +1'. The pentaquark, having a baryon number of +1, is a baryon. But unlike the usual baryon (qqq), its content is qqqqq. Thus it's an exotic baryon. I'm not super happy with the current wording because the logical steps aren't all shown, but I'm not sure how's the best way to present all of it. 18.4.2.1's suggestion isn't bad though. Headbomb {talk / contribs / physics / books} 20:52, 17 July 2015 (UTC)