Talk:Proton

incorrect structure

Adopt the change

Proton

incorrect

Proton

corrected

Was there discussion on this? I suppose since gluons can interact with gluons the previous one wasn't right, but now they must interact that way. Is there something in between? Gah4 (talk) 20:54, 4 November 2020 (UTC)

I would like to see included (not necessarily in the intro) a simple explanation of the meaning of each diagram, followed by an explanation of which one is correct and why. I don't think this is obvious to most readers. Dirac66 (talk) 03:19, 5 November 2020 (UTC)

I probably thought that the old one was close enough for most people. That there are quarks, and they interact through gluons. For most people that is probably enough. But since gluons can interact with each other, it does make sense to indicate that. But the picture then looks like gluons only interact in a three-way interaction, which isn't true. I suppose I don't know gluon statistics well enough. As well as I know, two gluons can interact, such that two go in and two go out. Are there two in one out, or one in two out, interactions like the diagram? Gah4 (talk) 06:32, 5 November 2020 (UTC)

See Talk:Proton/Archive_1#diagram of quarks in proton. The diagram does not represent gluon flux tubes, but rather interactions between quarks and gluons in general. This is intentional, and adopted across the board on Wikipedia, see Neutron, Antiproton, Antineutron, Nucleon, etc. If you want to change this, get consensus at WT:PHYS first. 23:58, 5 November 2020 (UTC)

It seems that Talk:Proton/Archive_1#diagram of quarks in proton is a few years old. I started a discussion in WT:PHYS as there isn't one so far. I did find this as a start to QCD diagrams. Gah4 (talk) 00:50, 6 November 2020 (UTC)

see: c:Commons:GL/I#Representation_of_the_gluon_field_in_the_nucleons --Mrmw (talk) 11:54, 16 November 2020 (UTC)

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This was discussed at length at Wikipedia talk:WikiProject Physics/Archive December 2020#quarks and gluons in diagrams and I thought there was a strong consensus that the Delta diagram was wrong and the Wye diagram was correct. So why does the article still show the Delta diagram? 67.198.37.16 (talk) 08:16, 14 February 2021 (UTC)

p.s. to reply to User:Dirac66 above, the discussion at WP:Physics included a derivation of the Wye diagram from "first principles", the QCD Lagrangian, and also explained what was wrong with the Delta diagram. Perhaps that explanation could be reworked into a form suitable for inclusion in this article. 67.198.37.16 (talk) 08:21, 14 February 2021 (UTC)

Reliable sources needed here

There seems to be a controversy as to which diagram (Δ or Y) is actually correct. As a chemist I will admit that I don't understand the arguments very well, but I do note that no one seems to have given a reliable source for either type of diagram. Which diagram is used in particle physics textbooks and review articles please? (My university library is closed for the pandemic.) If both are found widely in the literature, then WP:NPOV would require showing both types and summarizing the arguments for each. Reliable sources should be given for both points of view. Dirac66 (talk) 16:52, 14 February 2021 (UTC)

Tipler has a chart, but no diagram. Serway has a diagram, but no gluons are indicated. That is, neither Δ nor Y configuration is shown.—Anita5192 (talk) 17:34, 14 February 2021 (UTC)

Actual journal sources, if they have a diagram at all, should have the real Feynman diagram, including all loops and higher-order terms. The Y diagram seems wrong to me, as it requires a three gluon interaction, and for that matter, only allows for a three gluon interaction. But (as well as I know) there is everything from one (like Δ) up to infinity (that, as well as I know the story, need to get renormalized out). Gah4 (talk) 17:48, 14 February 2021 (UTC)

Sorry for the lack of formalism but saw the diagram and thought too it should be updated. Would the third image in this site count? Y diagram 20:43, 2 June 2021 (UTC) — Preceding unsigned comment added by 83.36.182.87 (talk)

I was at a physics seminar yesterday where this diagram came up. The diagram was on a slide, though mostly not covered by the talk. So I asked after the talk, and also for a WP:RS. It seems that it should be the wye diagram according to this reference. Gah4 (talk) 01:17, 24 April 2024 (UTC)

Seem like this reference is unequivocal:

• Bissey, F., Cao, F. G., Kitson, A. R., Signal, A. I., Leinweber, D. B., Lasscock, B. G., & Williams, A. G. (2007). Gluon flux-tube distribution and linear confinement in baryons. Physical Review D, 76(11), 114512.

It says:

• "We have analyzed 11 L-shapes and 8 T- and Y-shapes of varying sizes in order to explore a variety of flux-tube topologies, including the ground state. At large separations, Y-shape flux-tube formation is observed. T-shaped paths are observed to relax towards a Y-shaped topology, whereas L-shaped paths give rise to a large potential energy. We do not find any evidence for the formation of a Δ-shaped flux-tube (empty triangle) distribution. However, at small quark separations, we do observe an expulsion of gluon-field fluctuations in the shape of a filled triangle with maximal expulsion at the center of the triangle."

Johnjbarton (talk) 01:48, 24 April 2024 (UTC)

OK, there is one that I am now not sure about. When I was discussing this yesterday, the explanations had arrows on them. I think the picture here is the possible interactions, not a specific interaction. In the case of the delta diagram, I read it as three different interactions, in one diagram. (Much nicer than three separate drawings.) I think the ones in the Rossi paper, and also in the Bissey paper, are individual interactions. More specifically, all we need to indicate here is that there are gluons interacting with quarks. We don't need to indicate all the possible ways that they can interact, and avoid ones that they can't. Gah4 (talk) 02:31, 24 April 2024 (UTC)

References

reactions

As the article notes, Rutherford was first to discover nuclear reactions. Was he also the first to use the reaction notation similar to that used in chemistry? That is (reactants) arrow (products)? Gah4 (talk) 18:18, 11 February 2021 (UTC)

fundamentalness

Recent edits related to the fundamentalness of protons. As well as I know, they should be considered fundamental. Fundamental doesn't mean that they don't have internal structure or size, though. Since we don't have lone quarks, and quark-antiquark mesons aren't stable, it seems to be that protons are the most fundamental state of quark-based matter. Gah4 (talk) 05:45, 17 February 2021 (UTC)

hydronium

There is discussion about lone protons. I suspect that the reason this is a question at all is that chemists like to write H+ when they actually mean H3O+. If there are electrons around, and the temperature is not too high, it will grab one. High means plasma or, as noted, accelerators. Gah4 (talk) 14:26, 28 February 2021 (UTC)

Quarks and the mass of a proton

In Proton § Quarks and the mass of a proton, it says "As noted, most of a proton's mass comes from the gluons that bind the current quarks together, rather than from the quarks themselves." As I understand it, the confinement of the quarks forces them to relativistic velocities, with the resultant kinetic energy contributing significantly to the hadron's mass. Should the quoted sentence not be amended accordingly? —Quondum 02:36, 4 June 2021 (UTC)

Quondum, there is a newer source nicely explaining all the contributions to the mass at https://physics.aps.org/articles./v11/118. StarryGrandma (talk) 23:12, 4 June 2021 (UTC)

Not found.—Anita5192 (talk) 23:24, 4 June 2021 (UTC)

The correct URL is https://physics.aps.org/articles/v11/118 without the period after the word articles. Computers are very picky sometimes. Dirac66 (talk) 00:26, 5 June 2021 (UTC)

Thanks, that is far more understandable, and largely in line with what I had understood. The term "binding energy" seemed to be so misused that it was just confusing. I edited this in. —Quondum 01:25, 5 June 2021 (UTC)

NMR

The NMR section strongly (too strongly) indicates that it couples to spin. It actually couples to the magnetic moment, which of course is related to spin, but not exactly spin. For example, neutrons are also spin 1/2, but have a different magnetic moment. Gah4 (talk) 10:55, 15 February 2022 (UTC)

What wording would you suggest for that section? Dirac66 (talk) 03:12, 18 February 2022 (UTC)

How about spin magnetic moment which seems to be real enough to have its own page. Gah4 (talk) 10:47, 22 August 2022 (UTC)

Good idea, so I have rewritten the paragraph around the term "spin magnetic moment". Perhaps you can improve it further. Dirac66 (talk) 20:58, 22 August 2022 (UTC)

Potential charm quark in protons?

Recently I have learned of some new research indicating potential for an additional quark in protons and so am bringing this up to see how it should be addressed.

https://www.nature.com/articles/s41586-022-04998-2

Perhaps this should be mentioned under "Quarks and the mass of a proton" as unconfirmed, but relevant research? Should we wait instead or do something else? StellarRemant (talk) 19:56, 17 August 2022 (UTC)

additional secondary source is available here. — Preceding unsigned comment added by 151.19.204.39 (talk) 00:30, 20 August 2022 (UTC)

That result is only 3 sigma, which means it is not discovery. 109.252.168.16 (talk) 17:43, 20 August 2022 (UTC)

I didn't actually read the article, but at some point you can always have virtual quark-antiquark pairs. How many depends on the energy available, and quark masses. Gah4 (talk) 10:46, 22 August 2022 (UTC)

Rutherford's 1st proposed reaction

The article currently states that Rutherford proposed the reaction "¹⁴N + α → ¹⁴C + α + H⁺" ("History" section, 5th paragraph). But this equation has different mass numbers on each side: 18 on the left and 19 on the right. Is this a typo? Or maybe an incorrect transcription of Rutherford's proposal into modern notation? Should it be ¹⁴N + α → ¹³C + α + H⁺? Indefatigable (talk) 17:05, 19 October 2022 (UTC)

Possibly a typo when entered. But I've removed it as failing verification. The source doesn't mention a proposed reaction, only that Rutherford thought charged hydrogen atoms were torn off from the bombarded nucleus, implying that atomic nuclei of lighter elements were made up of combinations of hydrogen and helium. StarryGrandma (talk) 19:22, 19 October 2022 (UTC)

Charge radius

The section on charge radius is confusing. The story to be told here is 1) the value and meaning and 2) recent history of the value due to changes in types of experiments. These bits are mixed up and the section tails off with some math. Johnjbarton (talk) 16:50, 27 March 2024 (UTC)

I suspect there is no good way to explain charge radius without some math. The proton contains quarks and gluons moving at high speed, according to their Fermi velocity. As usual for quantum problems, there is an exponential tail. With appropriate math, one can come up with a single number to describe the radius. Different math will give a different number. Gah4 (talk) 20:17, 27 March 2024 (UTC)

Sorry I don't agree. The proton radius value is clearly and unambiguously defined and used in different kinds of theories and experiments.

• Miller, Gerald A. (2019-03-07). "Defining the proton radius: A unified treatment". Physical Review C. 99 (3). doi:10.1103/PhysRevC.99.035202. ISSN 2469-9985.

The Proton radius puzzle page is actually pretty good on the charge radius story. I made a lot of changes to it, please review. Johnjbarton (talk) 01:39, 28 March 2024 (UTC)

Sorry, I didn't explain it well. Once you define the expression for the radius, then it is well defined. Consider the Gaussian. The width could be FWHM or FWTM, but once you say which one, it is well defined. Anything with an infinite tail, which is pretty much everything in quantum mechanics, needs a nice definition. But someone else could come along, and use a different one. If you don't know anything about the charge distribution, which might apply to some readers, then you have to explain it all the way back. That would be especially true for less mathematical readers. Reminds me, there used to be a joke about the page Chlorine-releasing compounds defining them as compounds that release chlorine. Seems to have changed now, though. Gah4 (talk) 19:47, 28 March 2024 (UTC)

Yes, common, non-physicist meaning of "radius" is ambiguous for elementary particles. It would be great if we could find a ref explaining how the official def can be "interpreted". The bad news is that the interpretations I have found point to 2D parton models because all of the interactions involved are relativistic. So a vaguely spherical fuzzy ball is not a thing here. Johnjbarton (talk) 19:58, 28 March 2024 (UTC)

To be more specific, what is f(r/Rp)? That is, the radial part of the charge density function? Since protons have spin, they are not spherically symmetric, so there could be other terms besides radial dependence. Gah4 (talk) 02:30, 29 March 2024 (UTC)

The shape is not determined experimentally. Johnjbarton (talk) 16:18, 29 March 2024 (UTC)

So you see the problem of giving an exact size for something of unknown shape. I suspect this isn't a problem for physicists, but many others will read the article. Some might assume a ball of uniform charge and given radius. But yes, once you assume a specific charge distibution function, then you can measure it accurately, within that assumption. Gah4 (talk) 18:26, 29 March 2024 (UTC)

Yes I agree with your overall point. I just don't know how to address it with refs. Johnjbarton (talk) 20:46, 29 March 2024 (UTC)

This article has details:

• Gao, H.; Vanderhaeghen, M. (2022-01-21). "The proton charge radius". Reviews of Modern Physics. 94 (1). doi:10.1103/RevModPhys.94.015002. ISSN 0034-6861.

For example, in discussing data for hadrons:

• • "the transverse density at equal light-front times can be interpreted as a two dimensional flash photograph of a three-dimensional object"

Johnjbarton (talk) 15:48, 3 April 2024 (UTC)