# Talk:Weak interaction

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Weak interaction has been listed as one of the Natural sciences good articles under the good article criteria. If you can improve it further, please do so. If it no longer meets these criteria, you can reassess it.
Article milestones
DateProcessResult
April 6, 2011Good article nomineeListed
WikiProject Physics (Rated GA-class, Top-importance)
Wikipedia Version 1.0 Editorial Team / Vital (Rated GA-class)

## Neutral current Interaction wrong

The process

${\displaystyle e^{-}\to e^{-}+Z^{0}}$

cannot happen without another potential! It's the same as with

${\displaystyle e^{-}\to e^{-}+\gamma }$

which violates energy and momentum conservation. That's obvious if going to the electron's rest system! — Preceding unsigned comment added by 178.2.17.78 (talk) 03:00, 15 May 2013 (UTC)

## Violation of symmetry is ambiguous or wrong

The section on violation of symmetry states, in a kind of unclear (contextual) way, that the weak force violate CP symmetry. This is not the case. The 'bare' weak force preserves CP symmetry, whereas the weak force in the SM because of the SU(2)xSU(3) structure violates it. 83.89.32.26 (talk) 16:10, 21 April 2012 (UTC)

I'm wondering what use the authors of this page expect the page to be. The level of physics knowledge needed to comprehend this page is beyond that of anyone who would need to look up the subject of the page. I'd tackle trying to write a basic explanation, but I'm not a physicist, and would be afraid of making some basic errors. —Preceding unsigned comment added by 70.88.233.70 (talk) 17:21, 27 December 2007 (UTC)

Totally agree. It seems the article's only use is to tell PhD's in physics what they already know. Captain Quirk (talk) 04:55, 24 March 2011 (UTC)
Agree. The article is meaningless to anyone that does not already understand it. Tuntable (talk) 00:20, 31 March 2011 (UTC)

Disagree. Yes, it is extremely complex, however, in this format I will be able, should i choose to, and see it important enough, to follow the data and links, until I have as complete an understanding of the matter as I wish to. I'm sure there are simple explanations on the web for anyone seeking that; and perhaps a simple explanation as an aid would be good, however, I believe wikipedia's format allows anyone who wishes to have a true understanding of something to do so, and it should stay that way; not be (excuse the expression) "dumbed down" for the sake of simplicity. — Preceding unsigned comment added by 76.108.9.223 (talk) 19:37, 30 May 2012 (UTC)

There is a use for more detailed information. I have a Ph.D in semiconductor physics. I can usually understand descriptions of nuclear physics, but I don't already know them. That isn't to say that there shouldn't be useful material for non-physicists, or non-scientists in general. Even full-time nuclear physicists don't know everything, and need a reference book sometimes. If it takes a few years of schooling to understand, you can't expect to learn it all from one article. Gah4 (talk) 00:10, 13 June 2015 (UTC)
Dude! Not to be rude or anything, but if you have a PhD in Physics what in the world are you THINKING using Wikipedia as a "Reference Book" (in Physics)?!216.96.77.80 (talk) 17:16, 5 August 2015 (UTC)

I think he may be a Wikipedia contributor. I don't think he uses it as a "Reference Book" but as a platform for him to share his knowledge on this particular subject TappyDoggy365 (talk) 13:20, 18 November 2018 (UTC)

## Stellar fusion

The diproton article claims this is the force responsible for stellar fusion (limiting the rate). Why? It'd be nice to mention that here. --Andrew 05:25, Mar 31, 2005 (UTC)

Weak interactions occuour in stellar fusion because elements with more than one proton require a neutron to stop the protons from repelling each other with their + charges. Neutrons mutually attract the protons with strong force, and if weak interactions didn't take place, elements would be unable to fuse in stars.

## One or a half force

The statement that the weak force is one of the four fundamental forces cannot be true at the same time as the statement that there is an electroweak force which the weak force is an aspect of. Could someone please clarify this? --Etxrge 20:44, 9 May 2005 (UTC)

Quote from fundamental interaction:
Traditionally, physicists have counted four interactions: gravity, electromagnetism, the weak nuclear force, and the strong nuclear force. Their magnitude and behavior vary greatly, as can be seen in the table above. Yet, it is strongly believed that three of these interactions are manifestations of a single, more fundamental, interaction. Electromagnetism and the weak nuclear forces have been shown to be two aspects of a single electroweak force. Somewhat more speculatively, the electroweak force and the strong nuclear interaction have been combined using grand unified theories.

-- Rmrfstar 04:52, 15 August 2005 (UTC)

I suggest replacing "the four fundamental interactions of nature" with "the fundamental interactions of nature". A minor change but it is technically correct and is not going to cause any confusion. Mtpaley (talk) 23:12, 23 February 2014 (UTC)

## Why?

This is because, under current conditions in the known universe, the weak force behaves as if it were a separate force to all others (strong, electromagnetic, gravity). However, under certain conditions, the weak force and the electromagnetic force behave in the same way. Because of this, physicists view the weak nuclear force as part of an 'electroweak' force; however it is useful when applied to ideas concerning the universe as it currently stands to consider the weak force as a separate force to the others.

## Request for history

Can anyone provide a little history? Who first proposed the idea of this force and when? -- Mrnatural 02:51, 12 Jun, 2005 (UTC)

## nuclear force vs interaction

Should not this article be titled, "Weak interaction" as Strong interaction is? -- Rmrfstar 7 July 2005 17:49 (UTC)

## How many times weaker than strong nuclear force?

Fundamental interaction says weak nuclear force is 1025 times weaker than strong nuclear force. Weak nuclear force says it is just is 109 weaker. What is correct? Miraceti 13:34, 22 September 2005 (UTC)

In the Fundamental interaction page it's how many times stronger it is than gravity, on this page it's stating how much weaker it is than strong nuclear force.
The weak force is appparently 105 times weaker than the strong nuclear force. Reference: Pickering, A., Constructing Quarks (Edinburgh University Press, 1984). Any comments? —Preceding unsigned comment added by 144.82.106.37 (talk) 12:26, 24 April 2008 (UTC)
That's what Strong interaction says, too, and what drove me to the talk page, because this article currently says that Weak is 10−13 of strong. Someone's numbers are off. Rifter0x0000 (talk) 04:54, 18 February 2010 (UTC)
Actually, looking at Fundamental interaction, if you go by those numbers then 10−13 would be correct. Therefore, either Strong interaction and your source have it wrong, or it is wrong in at least two articles. The note on the column on relative strengths says "Approximate. The exact strengths depend on the particles and energies involved." It is unclear from the article what books are being used for what data, but all of the books referenced in the reference section are newer than the one you reference here. Strong interaction likewise does not specify where the numbers are from, but I am noticing that the books referenced in that article seem to be older than in Fundamental interaction. Without looking at the books and having a better background in this area, I couldn't tell you what numbers are right, but someone should correct this. Rifter0x0000 (talk) 05:06, 18 February 2010 (UTC)
Since gravity and electric force on a point both have the same dependence on distance, they can be directly compared. Even then, you have to specify the charge/mass of the particles used. It is more complicated for weak and strong, so a direct comparison isn't really useful. With some assumptions, one can come up with a number, but it will vary with the assumptions. Gah4 (talk) 00:15, 13 June 2015 (UTC)
What the above is TRYING to say is that the relative ranking of the four forces (which is stronger than which) depends on DISTANCE between the particles. The strong force is virtually ZERO over atomic distances, as is gravity. As distances 'shrink', the strong force increases exponentially. Similarily, as distances 'grow', gravity increases (but slowly, NOT exponentially). If you look at the Fundamental interaction article, you'll see in the table two different "scales", the table SHOULD have described them as "distance scales", not scales...although energy and mass and distance get mixed up once you get below atomic scales (sizes smaller than a hydrogen atom (ie including its electron cloud, thousands of times larger than a 'bare' proton or neutron)). So, what we have is gravity and electromagnetic force depends on 1/d² (inverse distance squared, meaning double the distance and the force drops to (½)² = ¼, or halve the distance and force increases by 4X.) while the weak and strong forces do NOT obey that relationship (and have their own separate relationships), so the ratio of S:E:W:G forces depends on the distance between (and the identity of) the particles in question. ANY NUMERIC values are computed at a specific distance separating two specific particles, the claim that S > E > W > G is only true for a certain range of choices of distance (and particles) at others G > E > W > S and yes, you can choose a situation where W is the "strongest" force. What's worse, some authors do NOT use the same distance (or particles) to calculate the forces: they use "typical" distances for each particular particle interaction, meaning that the strong interaction is between quarks at very small distances, the weak interaction is between nucleons at distances typical of an atomic nucleus, and the electromagnetic (and gravitational) force(s) are at atomic distances. In one important way, the three "understood" quantum forces (S,W,E) are the SAME at large distances: at "large enough" distances they are all zero (with "large enough" being drastically different for each of them). This is why gravity is the only force of significance at cosmological distances. It isn't because gravity is stronger; just the opposite. Its because the others are so strong that they've 'neutralized' themselves at "large enough" distances. (of course, we've not found any anti-gravity particles yet, so gravity is also the only force that isn't "neutralized", but its so weak that particle physicists can ignore it (except for cosmology, astrophysics, or when building a collider...).216.96.77.80 (talk) 18:02, 5 August 2015 (UTC)

## Attraction and/or Repulsion?

Does the weak nuclear force generate an attractive or repulsive force between two particles? The other 3 forces generate attractions and/or repulions, so shouldn't the weak nuclear force do the same thing, especially if it is supposed to be similar to the EM force?

The answer, oddly enough, is no. The weak force the same as the others in a fundamental sense, in that force-carrying bosons are exchanged. The difference is that the weak force, unlike all the other forces, is mediated by very heavy particles. Thus whereas two electrons can exchange many, many photons and so produce what's effectively a continuous repulsive force, they exchange relatively few Z bosons because they're so heavy. (Really, the Z bosons do make a very small contribution to electron repulsion.) I'm not sure if that helps or not, but there's a try. If you have more questions, the best place to ask is Wikipedia:Reference desk/Science. -- SCZenz 03:34, 26 December 2005 (UTC)

## Role in neutron decay?

Proton decay states that free neutrons decay in approximately 10 minutes due to weak interaction. Can someone add some details about this? Confuted 17:14, 26 March 2006 (UTC)

Neutron decay is beta decay at its most fundamental. I haven't looked at it, but the beta decay page should explain this. Gah4 (talk) 23:01, 7 June 2015 (UTC)
The following discussion is an archived debate of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

The result of the debate was move. —Nightstallion (?) 12:50, 3 March 2006 (UTC)

## Move to Weak interaction

1. because it's the modern name, rather than the historical one
2. because people get confused between nuclear force, strong nuclear force and weak nuclear force
3. because the strong interaction is already so named

-- Xerxes 18:39, 26 February 2006 (UTC)

### Voting

• Support as per reasons above. David Kernow 03:03, 27 February 2006 (UTC)
• Agree with Xerxes. Conscious 06:41, 28 February 2006 (UTC)
• Of course. —Nightstallion (?) 12:50, 3 March 2006 (UTC)
The above discussion is preserved as an archive of the debate. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

## Attraction and/or Repulsion, pt. II

Which pairs of weakly interacting particles attract each other and which repel each other via weak interaction? Is there any charge associated with weak interaction (such as electric charge in electromagnetism, or mass in gravity) that could be used to determine whether there will be attraction or repulsion between the particles caused by weak interaction? --193.198.16.211 (talk) 19:05, 5 June 2008 (UTC)

I believe the weak corollary to electromagnetic charge, color charge, and gravitational mass is weak isospin, though my understanding of the weak interaction is woefully inadequate. As for repulsion and attraction, I'm not sure if that plays a significant role in the weak interaction, which I think of more as a flavor-changing force. Eebster the Great (talk) 06:12, 29 January 2009 (UTC)
From the responses elsewhere it looks as if two electrons or two neutrinos would experience a slight repulsion, whereas an electron and a neutrino (which have opposite weak isospin) would experience a slight attraction. -- cheers, Michael C. Price talk 10:24, 6 January 2011 (UTC)

## Mathematical language

Seems impossible (or merely abstract) for anything to be more than one time less than another, yet the article states "the typical field strength is 1011 times less than the strength of the electromagnetic force and some 1013 times less than that of the strong force..." (A few statements on this page also use similar language.)

Though the electromagnetic force may be 1011 stronger than the typical field strength, that equation does not work in reverse. To simplify, field x is twice as strong as field y (x=2y), but you would not say that y is twice weaker (y=x-2x), you would say y is half weaker (y=.5x).

Apparently, the numbers that are hinted at in the article are extremely small fractions of the numbers being compared, but that is not what the language states. There must be a more accurate way of stating what is meant. —Preceding unsigned comment added by 64.142.36.94 (talk) 20:22, 10 September 2008 (UTC)

It has unfortunately become common to say stupid things like "Connecticut is ten times smaller than Pennsylvania". It would be more correct to say either "Connecticut is one tenth of the size of Pennsylvania", or "Pennsylvania is ten times larger than Connecticut". Just because pinhead TV journalists say things like this all the time, doesn't make it right. Feel free to change it.Eregli bob (talk) 06:41, 9 July 2012 (UTC)
'Connecticut has ten times the number of states per square kilometer...' Darryl from Mars (talk) 07:59, 6 August 2014 (UTC)

## corrections

had to fix a few glaring errors in this page, I'm surprised noone noticed them before, especially under 'properties' section... someone claimed that "It is the only action which violates parity symmetry P (because it almost never acts on left-handed particles). It is not the only one which violates CP (CP Symmetry)."... hmmm its a good thing they are wrong because if that were the case, then the sun would not shine, and we would not exist. the weak force acts ONLY on left handed particles, and right handed ANTIparticles. someone needs to go back to physics class before they start writing wiki articles. fixed a few typos too, but didn't get to all of them...could someone who actually has a degree try to clean up this very important article please? - donnie —Preceding unsigned comment added by 96.253.121.213 (talk) 19:46, 7 October 2008 (UTC)

I corrected the 'properties' section that donnie supposedly corrected before. Weak force couples to RIGHT-handed particles through the Z boson. The W, on the other hand, couples only to left-handed particles (right-handed anti-particles). When constructing the electroweak theory, you have the symmetry groups SU(2)xU(1): 4 gauge fields. The SU(2) group couples only to left-handed fields, while the U(1) couples to the hypercharge. Two of the fields from SU(2) can be related directly to the two W bosons. The other 2 fields cannot be directly related to a particle, they are mixed. From here you get the photon and the Z fields, which do not have the restriction of coupling only to left-handed particles. Fjpyanez (talk) 22:16, 5 January 2011 (UTC)

the violation of symmetry section badly needs cleanup —Preceding unsigned comment added by 96.253.121.213 (talk) 20:02, 7 October 2008 (UTC)

I fixed some mistakes and (hopefully) improved tha language of one section. Dauto (talk) 20:17, 27 January 2009 (UTC)

## Feynman Diagram is wrong

The arrow on the neutrino should point in the opposite direction. The W particle is about 100 times more massive than a neutron, which makes this interaction seem kind of ridiculous without a weird interpretation of the neutrino as traveling backward in time. Look at the neutron decay diagram referenced by the discussion page for beta decay for a correct treatment. --213.235.192.234 (talk) 17:47, 24 October 2008 (UTC)

I got it fixed at the Graphic Labs. Headbomb {ταλκWP Physics: PotW} 22:43, 24 October 2008 (UTC)

The arrow is backward or the particle is wrong. You either need a neutrino moving backward in time or an antineutrino moving forward in time. Right now, the picture shows an antineutrino moving backward in time, which is the equivalent of a neutrino going forward in time. The decay shown would therefore violate the conservation of lepton number. —Preceding unsigned comment added by 76.246.25.83 (talk) 22:44, 28 January 2009 (UTC)

I concur. 134.50.203.42 (talk) 17:51, 14 May 2009 (UTC)
Me too. -- cheers, Michael C. Price talk 10:33, 6 January 2011 (UTC)
The convention currently used in the figure is consistent with the one adopted by many popular QFT textbooks (e.g. Mandl-Shaw, Peskin-Schroeder). In that convention the arrows on fermion lines follow the flow of fermion number, therefore an antifermion in the final state is denoted by an arrow pointing towards the vertex (i.e. backwards in time). See this discussion on the talk page of the Feynman diagram article. On the other hand, I agree with the editor who wrote in Headbomb's talk page that the wiggly lines of gauge bosons usually don't have arrows. Cheers, Ptrslv72 (talk) 16:27, 17 January 2011 (UTC)
Yes, the antifermion's arrow points backwards - but it represents the fermion, not the anti-fermion. Hint: an anti-fermion is a fermion going back in time, not an antifermion going back in time. And Feynman agrees with me; see his QED: the strange story of light and matter pages 140 & 145. -- cheers, Michael C. Price talk 16:59, 17 January 2011 (UTC)
We already had this very same discussion once, but I'll give it one more try: in this convention the arrow does not denote the direction in which the fermion (or antifermion) itself travels in time. It rather denotes the flow of fermion number, the latter being 1 for a fermion and -1 for an antifermion. The creation of an antifermion in the final state subtracts one unit of fermion number from the final state, therefore the corresponding arrow points backwards (towards the vertex). I understand that this convention might seem confusing to you, but it is actually very useful in practical calculations (especially for more complicated diagrams) because it tells you the ordering of the operators on the fermion line when you write down the amplitude for the process.
Most importantly, this convention is widely used in modern QFT textbooks (in addition to those mentioned above, see e.g. also Weinberg, vol.1, section 8.6). Can you at least admit this, or not? Surely you are not claiming that those textbooks are all wrong. Are you? Cheers, Ptrslv72 (talk) 17:45, 17 January 2011 (UTC)
Some of my books disagree; most importantly the Feynman one does. BTW, the fermion flow is a red herring since we agree about the arrow's direction - it what it represents that is the issue, i.e. whether we label it as a fermion or anti-fermion, i.e. with a bar or without. -- cheers, Michael C. Price talk 17:52, 17 January 2011 (UTC)
NO, your books don't disagree with mine. Your books - including Feynman's - adopt a different convention. Is this such a difficult concept to grasp?
Look, I do not particularly care about which convention is used in the Wiki articles, as long as it is used consistently. The fact that previous editors seem to favor the convention of Peskin-Schroeder (in which the arrow on the outgoing-antifermion line points backwards but the particle is still labeled an antifermion) should tell you that that convention is more popular than the one you like. But this is not really the issue here, the issue is your persistent claim that the convention that you don't understand is "wrong". Cheers, Ptrslv72 (talk) 18:11, 17 January 2011 (UTC)
I have just inspected my 7 QFT books within arm's reach and looked at their beta decay diagrams. Two have no such diagrams. 4 have either the anti-fermion leaving the vertex and/or the fermion approaching (i.e. Feynman / my convention) and only one (Leite Lopes) has your choice of the anti-fermion approaching the vertex in places (and my choice in other places). -- cheers, Michael C. Price talk 03:16, 18 January 2011 (UTC)
You can inspect as may textbooks as you want but you sound like you still don't get it (BTW buy some modern ones, e.g. Peskin-Schroeder is excellent). In the convention of Peskin-Schroeder, Mandl-Shaw, Weinberg and who knows how many others, the antifermion is not "approaching the vertex", because the direction of the arrow does not denote the direction in which the particle travels in time (but rather, as I tried vainly to make you understand, the flow of fermion number). As Headbomb argues below, the diagram in this article identifies clearly an initial state (on the bottom) and a final state (on the top). Having a particle labeled as neutrino in the final state would be at least as confusing as having the antineutrino arrow pointing backwards. Cheers, Ptrslv72 (talk) 11:55, 18 January 2011 (UTC)
By saying the fermion "approached" the vertex I referred only to the way the arrow pointed. You taking that evidence that am clueless and not "getting" fermion number flow speaks volumes for your inability to be constructive. -- cheers, Michael C. Price talk 21:37, 18 January 2011 (UTC)
Ok, so you do get it. So much the better, if your stance has evolved from "the diagrams are all wrong" to "I don't like the convention" this discussion was not a complete waste of time. Cheers, Ptrslv72 (talk) 22:10, 18 January 2011 (UTC)
My stance has evolved in that I found that Feynman adopted the same convention that you now ignore. -- cheers, Michael C. Price talk 22:32, 18 January 2011 (UTC)
Huh? I don't understand what you mean with this. Do you stand by your earlier statements that the diagrams are all wrong, or you don't? But hey, I see we are entering "Dead Horse" zone... Ptrslv72 (talk) 22:47, 18 January 2011 (UTC)
Please don't start with an idiotic and patronising "Huh?". Sounds like you don't want an answer. If I'm I'm wrong, and you are genuinely interested, I will answer a polite enquiry. -- cheers, Michael C. Price talk 22:56, 18 January 2011 (UTC)
Please stop being offended by people who either disagree or don't understand you. "Huh?" is nowhere near idiotic or patronizing. 23:03, 18 January 2011 (UTC)
I respectively disagree, Headbomb, that starting a response "Huh?" is not patronising, especially when coupled with a gratuitious "dead horse" comment, which indicated a lack of interest in whatever I said. BTW, AGF does not mean I can't tell folks when they are being uncivil. -- cheers, Michael C. Price talk 00:08, 19 January 2011 (UTC)
What Ptrslv72 said. It's a matter of convention. Some label things as perceived by a outside observer going forward in time, others label everything as particles, and let the arrows speak of particle/antiparticles. I personally favour the "Peskin–Schroeder" approach for Wikipedia, as we're telling people "proton --> neutron + antineutrino", and they will see a diagram with "proton --> neutron + neutrino", creating a great mismatch being the visual representation of the process, and the text describing the process. Mentioning "a neutrino going backwards in time is an antineutrino" Everytime we use Feynman diagrams, will be confusing to several people and extremely annoying / cluttering. Were this a generic diagram, I'd probably follow the Feynman convention (but that's just me), since we'd be speaking of generic process regardless of orientation in time, but this isn't what is happening here. 23:03, 17 January 2011 (UTC)
You're right, that isn't happening here, and readers (not just me) are complaining that the diagrams are confused. -- cheers, Michael C. Price talk 03:16, 18 January 2011 (UTC)

And if it were switched around, other people would complain. Your point? 03:35, 18 January 2011 (UTC)

Well, you've said you would complain. Anyone else? -- cheers, Michael C. Price talk 03:40, 18 January 2011 (UTC)
I would too. And I don't think that two anonymous editors from two years ago count for your poll... Ptrslv72 (talk) 11:59, 18 January 2011 (UTC)
Interesting that you previously said: Look, I do not particularly care about which convention is used in the Wiki articles, as long as it is used consistently. -- cheers, Michael C. Price talk 21:37, 18 January 2011 (UTC)
I do not particularly care because I have no problem in understanding either convention (even though I normally use the one of Peskin). However, I take Headbomb's point (made after the statement you refer to) that showing a neutrino in the final state would be more confusing. Cheers, Ptrslv72 (talk) 22:03, 18 January 2011 (UTC)
This is also my position. I'm really not a fan of this convention however, although whether it ought to be changed or not I don't know. 23:03, 18 January 2011 (UTC)
In principle it would be better to choose one convention and stick to it, so I would favor changing that particular diagram if we decide to go for Peskin-Schroeder. But I balk at the idea of chasing Feynman diagrams all over Wikipedia... Ptrslv72 (talk) 23:52, 18 January 2011 (UTC)
On a procedural point, where would the convention be debated/decided, and where would it be recorded (to prevent endless reruns)? -- cheers, Michael C. Price talk 00:08, 19 January 2011 (UTC)
WT:PHYS seems the best place to have it, with notices on talk:Particle physics and talk:Feynman diagram and perhaps 2-3 more relevant articles. That is assuming there needs to be an RfC, which I doubt there is a need for it. 00:53, 19 January 2011 (UTC)

## Emission of electrons by protons...

In the article, "the emission of electrons by protons or positrons by neutrons in atomic nuclei" probably does not obey the charge conservation law. Or am I wrong? --FDominec (talk) 20:47, 10 June 2010 (UTC)

Yes, you are right (see e.g. http://en.wikipedia.org/wiki/Beta_decay). Could anyone correct this? -- 12 July 2010 (UTC) --

## Mistake

"Its most familiar effect is beta decay (or the emission of electrons by protons or positrons by neutrons in atomic nuclei) and the associated radioactivity"

the electron and positron has switched places

should be:

"emission of positrons by protons (forming neutrons) or electrons by neutrons (forming protons) in atomic nuclei" —Preceding unsigned comment added by 116.252.22.178 (talk) 06:22, 11 August 2010 (UTC)

## Z boson

Should the Z boson be mentioned in the weak interaction section? It seems to me that this is a prediction of electroweak theory, not a weak exchange particle. -- cheers, Michael C. Price talk 10:32, 6 January 2011 (UTC)

Weak interaction, as a low-energy manifestation of the electroweak force, needs the Z boson in order to be completely defined. If you take the historical approach, then the Z (or neutral current), entered the picture after the first attempts of building a weak theory, and I can understand your objection. However, in the current weak theory the Z boson plays an important role in many low-energy processes (by low-energy, I mean below the unification scale), like pure neutrino scattering, which can only take place through its exchange. Moreover, all books I've consulted about weak interaction (regardless of the difficulty) mention the Z. Fjpyanez (talk) 10:30, 7 January 2011 (UTC)
We seem agreed historically. I've just looked at Ta-Pei Cheng; Ling-Fong Li (1983). Gauge Theory of Elementary Particle Physics. ISBN 0198519613 which has an interesting subsection "Weak interactions before gauge theory" (pages 336-9) which explains the Fermi current and explicitly excludes neutral currents from the pre-unification weak interaction. -- cheers, Michael C. Price talk 11:39, 7 January 2011 (UTC)
One aspect that I forgot to mention is that if you explicitly exclude neutral currents, that opens the door to the statement "weak interaction involves only left-handed fields/particles", which is plain wrong. That was the correction that I originally wanted to make. We had a discussion about this during a seminar and a colleague looked it up later and found the error. On the other hand, I think that the request of 'Mrnatural' of providing a little history is well overdue, that would clarify the picture. I'll see if I have some time to start it, any help will be well received. Best, Fjpyanez (talk) 17:52, 7 January 2011 (UTC)
But is it plain wrong? Was the "error" the Z boson? I think if we get the historical context correct we can see that it may be correct. The weak interaction was only posited to explain, via radioactive decay, the creation (and destruction by implication) of neutrinos - which are all left handed. We're all agreed on the physics here, so it just a case of where we draw the boundary between the early weak interaction and the polished electroweak interaction. -- cheers, Michael C. Price talk 18:02, 7 January 2011 (UTC)
I definitely concur with your statement that we agree in the physics behind all of this. The question here is whether the article should reflect the "modern" view of weak interaction, as the electroweak interaction after symmetry is broken, or the original V-A / weak theory of left-handed fields. For simplicity, I think the original theory could be the one discussed in detail here, as long as the implications of electroweak unification are mentioned in a section. If that seems reasonable to the people interested and discussing the article, I can make some changes during the week to go in this direction. Best, Fjpyanez (talk) 13:13, 8 January 2011 (UTC)
Since we already have an electroweak article, I agree that it is the original theory should be discussed in detail here, along will how this fits into the modern electroweak theory. I'm a bit hazy on how the V-A currents relate to left-handed fields (V-A currents are composed of purely left-handed fermions?), so I look forward to being educated on the subject. -- cheers, Michael C. Price talk 13:59, 8 January 2011 (UTC)

## good explanation for non-scientists

I agree that this section should be made more accessible to the non-expert. For what it's worth, an excellent discussion of the weak interaction (and of particle physics and the fundamental forces) can be found at www.learner.org/courses/physics. This discussion is aimed at the non-scientist, yet goes into a reasonable amount of detail. (And, no, I am not associated in any way with the site or the people who developed it.) — Preceding unsigned comment added by Davem62 (talkcontribs) 21:00, 9 February 2011 (UTC)

## Changes

I've attempted to make the article easier to understand, mainly by a) simplifying the odd bit of language in a minor way and b) some reorganisation so the understandable is not mixed with the 'incomprehensible' (from a non-expert). I'm aware I may have introduced errors, but if you could pause before turning simplifications (none of which I believe are too extreme) into complicated but more precise language, this might help. Thanks. Grandiose (me, talk, contribs) 13:31, 26 February 2011 (UTC)

Hi Grandiose, I find this paragraph quite misleading:
The emission of a W+ or W− boson either raises or lowers the electric charge of the emitting particle by one unit, and also alters the spin by one unit. At the same time, the emission or absorption of a W boson can change the type of the particle – for example changing a strange quark into an up quark. The neutral Z boson cannot change the electric charge of any particle, nor can it change any other of the so-called "charges" (such as strangeness, baryon number, charm, etc.). The emission or absorption of a Z boson can only change the spin, momentum, and energy of the other particle.
mass, charge and spin are intrinsic properties of a given elementary particle, and they cannot be changed by the emission (or absorption) of gauge bosons. In fact, as you write in the second sentence, the emission of a W turns a particle into a different particle - it does not "raise or lower" its charge or spin. Even in the case of Z emission (which does not turn a particle in a different particle), the spin of the emitting particle does not change. Only the direction of the spin (e.g. with respect to the particle's momentum) can change. To be more explicit: a spin-1/2 particle (e.g. an electron) emitting a Z boson remains a spin-1/2 particle. Similarly, a spin-0 particle (e.g. a Higgs boson) remains a spin-0 particle, and so on. I think that this paragraph should be rewritten or perhaps simply expunged. Cheers, Ptrslv72 (talk) 13:43, 2 March 2011 (UTC)
That one wasn't me, but that of course doesn't mean that inaccuracies don't need fixing. Grandiose (me, talk, contribs) 17:28, 2 March 2011 (UTC)
Oh, I see now that you took the paragraph from the W and Z bosons article. Well, it is misleading/incorrect even there ;-) Cheers, Ptrslv72 (talk) 01:57, 3 March 2011 (UTC)
Hi, do we really need to cite an unpublished pdf document from some guy in the internet for the table of weak isospin assignments in the Standard Model? I don't think that the source is appropriate for Wikipedia, and the information can anyway be found in any textbook. Cheers, Ptrslv72 (talk) 12:36, 4 March 2011 (UTC)
It's not perfect, but the author is well respected, has been published before, etc. I couldn't find a better source that detailed these directly. If you can, please change it. Grandiose (me, talk, contribs) 15:46, 4 March 2011 (UTC)
I seriously don't know what makes you think that "the author is well respected" (he appears to be some kind of blogger who had two papers published in low-tier journals), anyway that is besides the point. First of all there are Wiki policies against using unpublished material as source. Second, the information contained in the table is so trivial that it looks really weird to quote a "research" paper to support it. We should either quote a (published) review paper on the Standard Model, or quote a textbook, or perhaps just drop the citation. I might take care of it next week. Cheers, Ptrslv72 (talk) 00:17, 5 March 2011 (UTC)
On a second thought, quoting a textbook might not be wise because most of the readers won't have access to it. I found another reference which, while still not perfect (it's on the arXiv, but not published in a journal), has in my opinion several advantages over the old one: 1) one of the authors is a tenured physicist; 2) it's a review paper, as opposed to a research paper that just happen to contain the weak isospin assignments; 3) it is fully available in html format. Better alternatives will of course be welcome. Cheers, Ptrslv72 (talk) 16:14, 7 March 2011 (UTC)

32.178.171.35 (talk) 03:11, 9 March 2011 (UTC) Suggest adding the following link back to the definition of the 4 fundamental forces to aid the novice: http://en.wikipedia.org/wiki/Four_fundamental_forces perhaps via hyperlink at "forces or interactions". - Nick 8 March 2011 32.178.171.35 (talk) 03:11, 9 March 2011 (UTC)

## More changes

I removed this paragraph added by editor Poppit:

Whereras the strong nuclear force is the binding force which bonds quarks to one another to form hadrons, such as protons and neutrons, the weak nuclear force binds together the individual quarks. Weak decay, usually in the form of beta decay, is the symptom of an individual quark decaying, typically into a different type of (lower mass) quark.

First of all, the weak force affects both quarks and leptons. Second, quarks and leptons are elementary particles. What does Poppit mean when he writes that "individual quarks" are "bound together" by the weak force? Ptrslv72 (talk) 16:55, 11 March 2011 (UTC)

Incidentally, this other sentence is also misleading:

Where the boson is emitted (i.e. a W boson), it immediately decays. The decay products are predictable in accordance with another well understood set of probabilities. The highest proabability is that it will decay either into an electron and an electron anti-neutrino, or into a positron and an electron neutrino:

in principle a real W boson can decay with equal probability in any charged-lepton+neutrino pair. The probability for decays into quark pairs are more complicated due to the CKM mixing, but the total probability for decays into quarks is roughly twice the total probability for decays into leptons. However, we are talking here of a virtual W boson emitted in the decay of a real quark. Only the decay channels in which the sum of the masses of the decay products is smaller than the mass of the parent particle are allowed. This is why a down quark can only decay in an up quark plus electron and neutrino, while the decay of a charm quark might also involve a muon (or be purely hadronic). The idea that we can decompose the decay in 1) a quark decaying in another quark and a W boson with 2) the W subsequently decaying in leptons (or lighter quarks) as if they were independent processes is too simplistic. Ptrslv72 (talk) 17:34, 11 March 2011 (UTC)

I also notice that the classification of "three basic types of weak interaction" in the section Interaction types is a mess. The first sentence states that the first type is the neutral-current interaction, and then there are two types of charged-current interaction. However, the next sentence says that the first type is the charged-current interaction of leptons. This is contradictory. Furthermore, it is not clear to me what, in the writer's mind, distinguishes "the other two types" described afterwards. Both involve an up-type quark, a down-type quark and a W. I would say that there are only two basic types of weak interaction (charged or neutral), and that each of them can involve either quarks or leptons. In summary, the section should be substantially rewritten. Cheers, Ptrslv72 (talk) 13:10, 12 March 2011 (UTC)

OK, I've salvaged what I think is reasonable from Poppit's contributions, and made the above change (reducing it to two possible interactions). What are your thoughts? Grandiose (me, talk, contribs) 16:54, 12 March 2011 (UTC)
I've made a few extra changes hoping to further clarify that W decay and exchange of a virtual W are different concepts. Cheers, Ptrslv72 (talk) 18:40, 13 March 2011 (UTC)

## Charged current explanation

I don't really understand what this statement is trying to say, because particles involved in the neutral current reaction can also be charged. Could anyone make it clearer?

"The first type is called the "charged current interaction", because the particles which interact through it carry an electric charge, and is responsible for the beta decay phenomenon."

--Physics is all gnomes (talk) 19:04, 14 March 2011 (UTC)

I took it from charged current, more or less. Grandiose (me, talk, contribs) 19:11, 14 March 2011 (UTC)
Ok, I don't think it makes much sense at the moment though. (I mean the "because the particles which interact through it carry an electric charge" part.) I don't fully understand the charged current article, which is very technical - hopefully we can make weak interaction a bit more comprehensible than charged current is. --Physics is all gnomes (talk) 19:32, 14 March 2011 (UTC)

The names "charged" or "neutral" are in fact related to the charge of the vector boson: interactions mediated by a W are charged, while interactions mediated by a Z are neutral. Cheers, Ptrslv72 (talk) 23:47, 14 March 2011 (UTC)

BTW, I see that what I write above is in contradiction with a sentence in the charged current article, but I don't care. The point of that sentence is that, e.g., the fermionic current up->down (or electron->neutrino) involves a change of electric charge of -1 (or +1), and that's why it's called "charged current". However, in a gauge theory this is perfectly equivalent to saying that the vector boson associated to the interaction is charged. The statement "is incorrectly believed" reflects some personal quibble of one editor. Cheers, Ptrslv72 (talk) 00:02, 15 March 2011 (UTC)

Thanks for the explanation. If people agree with this, then we should also remove the "incorrectly believed" comment from the charged current article to avoid contradicting ourselves.--Physics is all gnomes (talk) 13:44, 15 March 2011 (UTC)

In fact, the above is wrong: the charged current and the neutral current are not labeled such because of the charge of the bosons or the change of electric charge. If that were the case, they'd be called the "charged boson interaction" and the "neutral boson interaction." They are labeled by the electric charge held by the weak currents: the weak current of an electron and a neutrino has an electric charge of -1. The Weak current of an electron with an anti-electron has an electric charge of 0. The interaction is blind to the electric charge (it is after all a weak interaction not an electromagnetic one). This is further evidenced by the naming convention predating the concept of the weak bosons.

## Consequences of weak interaction for non-technical audience

The press release of the 1979 Nobel prize for Glashow, Salam and Weinberg has some nice information for a general audience on the consequences of the weak interaction. Do you think we could we add a quote of some or all of this paragraph, or otherwise include this information somewhere in the article?

Although the weak interaction is much weaker than both the strong and the electromagnetic interactions, it is of great importance in many connections. The actual strength of the weak interaction is also of significance. The energy of the sun, all-important for life on earth, is produced when hydrogen fuses or burns into helium in a chain of nuclear reactions occurring in the interior of the sun. The first reaction in this chain, the transformation of hydrogen into heavy hydrogen (deuterium), is caused by the weak force. Without this force solar energy production would not be possible. Again, had the weak force been much stronger, the life span of the sun would have been too short for life to have had time to evolve on any planet. The weak interaction finds practical application in the radioactive elements used in medicine and technology, which are in general beta-radioactive, and in the beta-decay of a carbon isotope into nitrogen, which is the basis for the carbon-14 method for dating of organic archaeological remains.

— Press Release: The 1979 Nobel Prize in Physics [1]

--Physics is all gnomes (talk) 20:44, 14 March 2011 (UTC)

## Changes to the Introduction

I removed two recently-added sentences that sounded nonsensical:

It is not clear why spontaneous weak decay occurs, i.e. what causes a quark to decay into a lower energy state; but it is theorised that it may be due to the Higgs mechanism.

it's very clear why quarks decay: they emit a virtual W boson and are converted in a lighter quark. That's indeed clearly explained the article. I wonder why the person who wrote that sentence thinks that "it may due to the Higgs mechanism". Before even thinking of reinstating the sentence, please explain that.

The weak interaction typically results in the liberation of electrons, the particles which govern electromagnetism.

As we also explain in the article, the weak interaction affects all quarks and leptons (not just electrons). And what does it mean that electrons "govern electromagnetism"?

Also, the sentence about binding energy sounds fishy to me (to start with, force and energy are two different concepts!). Could the person who wrote it please elaborate on what it means, and provide references?

Cheers, Ptrslv72 (talk) 23:26, 15 March 2011 (UTC)

Seems to me

they emit a virtual W boson and are converted in a lighter quark

says how they decay, not why. Why, as in what causes the decay, what triggers it? Consider why did George Mallory climb Mount Everest: "Because it's there.". Gah4 (talk) 23:22, 5 August 2015 (UTC)

## Accessibility against encyclopaedic value

Recent edits (particularly by Stephen Poppitt) have brought to the forefront a couple of issues. Personally, I find that some of it amounts to a technical witchhunt, in the sense that we lose some important things: encyclopaedic tone, and readability in general. Consider this edit, for example. Quantum superpositions are pretty complicated, and really only useful for the expert reader (in my experience, degree level or above). I don't really think we need to aim the explanation of them to a much lower audience here. Summaries in a few words are likely to fail to get the point across - anything with quantum probabilities, etc, is likely to go over casual readers, and I dare say "(that is to say, it has a possibility of becoming any one of the three up-type quarks)" is actually more confusing. The casual reader can, as it stands, accept that there is something 'slightly weird' going on, and read further if he/she wants, else skip over. I think this point should be kept in mind. Similarly CP-parity violations, for example, needs (as it has been since I arrived) suitably excluded from the more understandable bits. Whilst you could spend all day explaining everything about it, this is not the place, and certainly not to try and bring it down to an elementary level. Grandiose (me, talk, contribs) 20:10, 16 March 2011 (UTC)

My main problem with Stephen Poppitt's edits is that they are often sloppily termed (physicswise, of course) or misleading, and sometimes they seem to reveal a quite poor understanding of the subject. I have given several examples in the sections above. I have now reverted some edits that I found unacceptable, I would beg Stephen Poppitt to come to the talk page and argue for his changes before implementing them in the article. I have a decent knowledge of the topic and I'll be glad to help (as long as the discussion is confined to improvements in the article, as per talk page guidelines). Cheers, Ptrslv72 (talk) 12:26, 17 March 2011 (UTC)
You apparantly assumed, for I never said so, that I have qualifications in physics or math. I don't. My presence here is not because I believe I can add anything to the science.
I am merely the average reader, trying to understand the article. I was interested enough to read it, and those articles to which it links, and re-read it. I then tried to make some revisions which I hoped might make it less baffling to an average reader; but only as clarifications.
I cannot debate the science with you. Whatever you tell me is the state of scientific knowledge, I accept without objection. My input is purely from the point of view of whether the article meets the moderator's objection that its definitions are circular, and its language too specialised to be understood by a non-physicist.
Stephen Poppitt 12:46, 19 March 2011 (UTC)
I understand your point of view, and I appreciate that you are trying to help. However, adding incorrect or misleading statements does not make the article more useful to the average reader, in fact it makes it less so. Especially since you know that you are not an expert, you should discuss changes to the article in the talk page before implementing them. And if somebody reverts your changes arguing that they are incorrect (as happened above) you should pause (and discuss) before reinstating them. Cheers, Ptrslv72 (talk) 12:54, 19 March 2011 (UTC)
Hi Stephen Poppit,
We definitely need people like you helping us to make the article more accessible. Can I suggest that you discuss the things you think should be changed on this talk page, being as specific as possible? I think we could make a lot of progress in the article by having a layman point out confusing bits and the experts fixing them.
In general, I think some parts of this topic are unavoidably technical, but other parts ought to be explainable to the average reader with an interest in physics.--Physics is all gnomes (talk) 13:11, 19 March 2011 (UTC)

## Is that true?

The article states: "According to the electroweak theory, at very high energies, the universe has four massless gauge boson fields similar to the photon and a complex scalar Higgs field doublet". I don't think that is correct. The prediction of four massless gauge bosons at very high energies is not a part of the electroweak theory itself (or the Standard model) as far as I can tell. Dauto (talk) 21:16, 19 March 2011 (UTC)

You probably already have, but ref #20 looks promising for this. Not sure though, it does go a little over me. Grandiose (me, talk, contribs) 21:50, 19 March 2011 (UTC)
Actually, I can't find it in there. Can we find something or someone else that makes that prediction? Grandiose (me, talk, contribs) 21:54, 19 March 2011 (UTC)
There are indeed four gauge bosons in the electroweak theory (i.e., three for SU(2) and one for U(1)). I suppose that whoever wrote the sentence just meant that at very high energies (i.e., energies much larger than ~100 GeV, the scale of electroweak symmetry breaking) the electroweak symmetry can approximately be considered exact, and the four gauge bosons can approximately be considered massless (just because their mass is much smaller than the typical energy of the considered processes). It's a quite trivial statement if you think about it. Cheers, Ptrslv72 (talk) 00:57, 21 March 2011 (UTC)
Yes, what you said is a trivial statement, but that is NOT what is written in the article. The article states that electroweak theory predicts that at some high energy (Temperature would be a better term) exact electroweak symmetry is restored leading to four massless vector gauge bosons. The problem is that that prediction belongs to theories beyond electroweak theory and the standard model such as supersymmetry or Technicolor (physics). Dauto (talk) 02:29, 21 March 2011 (UTC)
But the electroweak theory does predict that at a critical temperature of about mH/g there is a phase transition above which the SU(2)xU(1) symmetry of the electroweak theory is restored (and the gauge bosons are massless). This does not require any new physics like SUSY or technicolor. (Although these do effect various properties of the phase transition like the latent heat, etc.) There is a lots of literature on this. Just search for "electroweak phase transition" on google scholar. TR 08:54, 21 March 2011 (UTC)
OK, I see. it's a transition similar to the one that occurs for magnets at the Currie temperature. Thank you. Dauto (talk) 09:28, 21 March 2011 (UTC)

## Missing coverage?

I'm hoping to get this to GA standard in time for this round of the Wikicup, and that means starting the review process fairly soon. Are the any holes people can see in the coverage? Errors in the physics are clearly being addressed, and at least mostly have been. As far as teh imp[lications of weak decay, that's not mostly for this page - except giving links. Are there any pages that should be linked? Grandiose (me, talk, contribs) 20:39, 21 March 2011 (UTC)

The article has a session about weak isospin but says nothing about weak hypercharge which is just as important. Dauto (talk) 21:27, 21 March 2011 (UTC)
The physics is getting there, but I think there's still room for improvement on the accessibility front. How about a history section? A 'consequences' type section as suggested above? --Physics is all gnomes (talk) 11:54, 22 March 2011 (UTC)
Weak hypercharge - definitely needs information on that (maybe conjoined with the "weak isospin" section); history - seems to inextricable from the P and CP parity sections, and the electroweak section; 'consequences' - more, probably in lead for the time being unless it gets too much? Grandiose (me, talk, contribs) 17:14, 22 March 2011 (UTC)
The problem of this article is that at some point we need to set a boundary between the old-fashioned "weak interaction" (i.e. the description of the interaction in terms of a contact force between fermionic currents) and the modern description of the interaction in terms of a spontaneously broken gauge theory (i.e. the electroweak theory). Just an example: when we write that the strength of the weak interaction is much weaker than that of the electromagnetic interaction, we are referring only to the strength of the four-fermion (i.e. contact) interaction. Indeed, the strength of the couplings between two fermions and a Z or W boson (the ones that we detail in the section "Interaction Types") is of the same order of magnitude as the strength of the coupling between two charged fermions and a photon. However, the large mass of the exchanged Z and W bosons makes the corresponding four-fermion interaction look weak in comparison to the electromagnetic interaction.
My concern is that the more info we add about, e.g., the weak hypercharge, the more the article morphs into (and duplicates) the article on electroweak interaction. Perhaps we should stick to a historical perspective? Incidentally, I wonder if the slightly technical section "Interaction types" should be moved further down in the article. Cheers, Ptrslv72 (talk) 12:35, 23 March 2011 (UTC)
I agree (in my understanding) with the first point. Perhaps we could identify those things only true in the old-style model and group them together with an explanatory sentence. However, I disagree about one or two things you mention. Making this article historical in nature would be a bad idea IMO; it is the landing page for the vast majority of readers about the topic. I'm not too worried about similarities with the electroweak theory article, which has (from my perspective) a load of impenetrable technical maths in it. There might be articles where this could be a problem, but, as I'm confident weak isospin is not one of them, I am yet to find one. Grandiose (me, talk, contribs) 20:15, 23 March 2011 (UTC)

## GA Review

Reviewer: Tea with toast (talk) 03:24, 31 March 2011 (UTC)

### Problems needing to be addressed

The article looks to be in pretty good shape; however, there are several errors in the references:

• Refs 7 and 11 need more complete publishing info (publisher and ISBN, if available)
• All books should have ISBN where available. It looks like Refs 3, 10, and 17 need them.
• I assume that Refs 8 and 9 are citing the same book as Ref 10. Please list the full publishing info for the Cottingham & Greenwood book under the "Texts" subsection, and then complete Refs 8, 9, and 10 with "Cottingham & Greenwood (1986, 2001), p.#"

Other than those details, I am impressed by the quality of the article. I think it does a fairly good job of explaining the more technical things to a lay audience. I am not entirely satisfied by the way the "Weak isospin" and "Weak hypercharge" subsections are presented. They just don't seem to flow very well, and I don't quite understand the subject matter in them and how it relates to the rest of the article (Although this could just be a lack of understanding on my behalf). It is not a large enough problem to prevent me from passing this article, but it should be addressed if this article goes up for FA review (which I hope it does). Overall, great job. --Tea with toast (talk) 04:25, 31 March 2011 (UTC)

OK, I think I've covered the ref issues. #11 isn't a book per se, so I've provided what information I can. Grandiose (me, talk, contribs) 14:16, 2 April 2011 (UTC)

### Final review

GA review – see WP:WIAGA for criteria

1. Is it reasonably well written?
A. Prose quality:
B. MoS compliance for lead, layout, words to watch, fiction, and lists:
2. Is it factually accurate and verifiable?
A. References to sources:
B. Citation of reliable sources where necessary:
C. No original research:
3. Is it broad in its coverage?
A. Major aspects:
B. Focused:
4. Is it neutral?
Fair representation without bias:
5. Is it stable?
No edit wars, etc:
6. Does it contain images to illustrate the topic?
A. Images are copyright tagged, and non-free images have fair use rationales:
B. Images are provided where possible and appropriate, with suitable captions:
7. Overall:
Pass or Fail:
Good job! --Tea with toast (talk) 03:00, 6 April 2011 (UTC)

## Weak Isospin

Hi, I am uncomfortable with this sentence in the "Weak isospin" subsection:

Weak isospin (T3) is a property of all particles, which governs how particles interact (and in particular which particles) in the weak interaction. Weak isospin is a quantum number; particles not involved in the weak interactions have a value of 0.

In fact, weak isospin determines how particles interact with the SU(2) part of the electroweak interaction. Left-handed fermions have weak isospin of +-1/2, while right-handed fermions have weak isospin 0. As a result, right-handed fermions do not interact with W bosons. However, even right-handed fermions have non-zero hypercharge, therefore they do interact with Z bosons. In the sentence above we appear to be saying that, e.g., the interaction of a right-handed electron with a Z boson is not "weak interaction". This leads us back to the issue (discussed a few sections above) of what we really mean by weak interaction, as opposed to the modern description of electroweak interaction. Cheers, Ptrslv72 (talk) 09:26, 7 April 2011 (UTC)

I suggest merging the sections, in fact I might be bold and do it myself if I get the chance. That way, we can make it clear about right-handed antiparticles (for example). Grandiose (me, talk, contribs) 17:53, 7 April 2011 (UTC)

## Production of deuterium vs beta decay

Isn't the production of deuterium in stars a result of the beta decay of Helium-2? (Whose more common decay mode is double proton emission, of course.) Hcobb (talk) 01:45, 9 May 2012 (UTC)

## Move discussion in progress

There is a move discussion in progress on Talk:Fundamental interaction which affects this page. Please participate on that page and not in this talk page section. Thank you. —RMCD bot 11:58, 24 June 2013 (UTC)

## Electro weak theory section needs updating

the way the section talks about higgs bosons is out of date with the main article about higgs bosons Higgs_boson — Preceding unsigned comment added by 41.42.5.57 (talk) 03:16, 28 August 2013 (UTC)

## Fission?

The article mentions fission as an example of weak interaction. As I understood it, it is the result of the strong interaction (liquid drop model) and electromagnetic repulsion of the protons. I don't count the beta decay in fission products as part of fission itself. Thermal neutron fission also depends on neutron energy levels in the nucleus. Is that related to weak interaction? Gah4 (talk) 05:58, 8 June 2015 (UTC)

Having just tweeked the sentence on this in the first paragraph of the lede, I agree it is a little odd. Contemplating what the intention was, I think the notion was that the weak interaction comes into play after fission when the resulting fragments are neutron rich, hence undergo beta decay. Hence the intense flux of neutrinos from nuclear reactors. Perhaps also responsible at some point for neutrons that induce fission? It does need better clarity (if not correction). Bdushaw (talk) 18:35, 12 June 2015 (UTC)
OK, but if it is after fission, then it isn't really part of fission. More specifically, it doesn't affect the fission rate. I suppose decay of fission products is part of the energy generated in a fission power plant. Much of it is too delayed to matter in a bomb. Unless there is a reference for it, I would suggest removing the comment. Gah4 (talk) 00:18, 13 June 2015 (UTC)
I have no clear opinion on how to proceed, other than I agree something should be done. The weak interaction seems to be playing a role in, while not a fission event itself, the fission process. For example, the chain of reactions leading to plutonium requires transmutations by beta decay. But if one were to assemble an A-bomb and then turn off the weak interaction, would the bomb still explode? I think so... But I suspect nuclear reactions would not proceed the same way in the absence of the weak interaction. A reference would certainly be essential. Bdushaw (talk) 20:10, 13 June 2015 (UTC)

## Assessment comment

The comment(s) below were originally left at Talk:Weak interaction/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

 Lacks references Snailwalker | talk 00:59, 21 October 2006 (UTC)

Last edited at 00:59, 21 October 2006 (UTC). Substituted at 10:20, 30 April 2016 (UTC)

## Intro.

I just want to thank all the editors who wrote and crafted this well-written introductory paragraph. Bearian (talk) 18:42, 12 September 2016 (UTC)

## Intro

I join those who ask for a little more. (See sections "Some help here please" and others). I'm a pretty bright guy (I've been an invited guest lecturer at MIT in my field), but I'm not getting information here that helps me understand.

I think the problem is that the whole article is directed to "looking down" to the underlying quantum causes. The intro would be a lot clearer if it had a paragraph "looking up" to effects, maybe a list of the effects visible vis-a-vis the basic Bohr particles we're more familiar with. I think the starting point is just a list of phenomena:

• beta decay (and a phrase or two about how two protons get kicked out of the nucleus)
• decay of a neutron into a proton, electron, and neutrino
• what else? — Preceding unsigned comment added by 50.169.56.27 (talk) 13:09, 25 November 2016 (UTC)

## electromagnetic coupling constant

the value of g_em ist given with :${\displaystyle {\frac {e}{\sqrt {\varepsilon _{0}\hbar c}}}={\sqrt {4\pi \alpha }}\approx 0.30282212}$ in the article Coupling_constant#Gauge_coupling, that is far more than the here mentioned 1/100! Ra-raisch (talk) 21:23, 17 December 2016 (UTC)

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With Heisenberg's uncertainty a radius of action may be explained. At speed of light the range would be (using reduced Compton wave-length rC = λC / 2π):

${\displaystyle r_{c}=c_{0}t_{v}=\hbar /2c_{0}m=r_{C}/2}$.

Regarding kinetic energy and relativity the speed of light is not optimal for a long range:

${\displaystyle r_{v}=v_{v}t_{v}=v_{v}\hbar /2c_{0}^{2}m\gamma \leq {\text{max}}(\beta /\gamma )\cdot r_{C}/2}$,

but with max${\displaystyle (\beta /\gamma )={\sqrt {{\text{max}}(\beta ^{2}-\beta ^{4})}}=1/2}$ at ${\displaystyle v=c/{\sqrt {2}}=0,7071\,c}$ the expected range of action may be calculated estimated:

${\displaystyle r_{L}=r_{C}/4}$.

This gives for (${\displaystyle m_{Z}\approx m_{W}\approx 1,5\cdot 10^{-25}}$kg):

${\displaystyle r_{w}={\text{max}}({\tfrac {\beta }{\gamma }})r_{C}/2=r_{C}/4<0,7\cdot 10^{-18}}$ m.

Ra-raisch (talk) 20:09, 11 August 2017 (UTC)

## Speed of decay

The article says that "A particularly extreme example is the weak-force decay of a free neutron, which takes about 15 minutes". Does this mean literally that the decay starts at a given time and takes 15 minutes or does it mean that free neutrons last for 15 minutes (presumably on average) before decaying, and the speed of the actual decay is quicker? If it's actually a 15 minute decay process, how is that observed and what is going on to take so long? If it's not, the article would benefit from clarification of speed of decay versus time before decay. 85.211.230.100 (talk) 12:10, 8 May 2018 (UTC)

Sigh... you are inventing a bogus issue out of whole cloth. There are already sufficiently many wikilinks in the article to particle decay, radioactive decay, etc... to dispel any bogus expectations of a "speed of decay" issue. All time constants and adjectives "fast", "slow", etc... always refer only to survival probabilities in QM and particle physics. I would think that "any" discussion of such a bogus "versus" conceptual dichotomy would only muddy the waters and invite the reader to "absolutely Not think about condors flying in the sunset laying eggs in flight"! 13:44, 8 May 2018 (UTC)

## "Interaction"

I'm confused - how is the weak interaction an interaction? It seems to me that there's only one particle at the start of any "weak interaction", so what's it interacting with? Like, beta-decay, you start with a neutron, which then emits a W- boson which subsequently decays. So, what's the neutron interacting with initially? What am I missing? XinaNicole (talk) 17:41, 24 June 2018 (UTC)

In relativistic quantum field theory distinctions between past and future are rendered moot by line reversal. So the neutron interacts with the proton and the W it mutates to, or, in summary, the proton, electron and antineutrino in its future. Formally, the interaction is the same as an antineutrino interacting with a neutron to produce a proton and an electron.Cuzkatzimhut (talk) 19:02, 24 June 2018 (UTC)

## Weak Charged-current Interactions

May citations on experimental results be provided?

For leptons, is there any central tendency for a neutrino to absorb a W boson at a particular phase in oscillation?

For quarks, are CKM matrix elements an aggregation of varieties of interactions taking and, consequently, the observed flavour change? For example, under beta decay, a down quark changes to an up quark and this interaction contributes to the (0,0) CKM cell value? Are elements of the CKM matrix useful in designating the probability a charged-current interaction changes a quark to a particular flavour, as described in the section on interaction types? May kinds of interactions be listed? — Preceding unsigned comment added by 65.183.152.130 (talk) 02:10, 15 March 2022 (UTC)