Talk:Proton decay

The way this article is worded it presumes that proton decay actually occurs, when there is no evidence as yet that it actually does, just several theories which predict it. (IIRC, experimental evidence so far indicates that if it occurs at all, it takes a lot longer than many GUT candidates predict.)

I've gone ahead and changed the article so it doesn't misstate the current consensus. Re the experimental evidence, the lower limit is evidence against the existence of decay, but it had been presented as if it was evidence in its favor; that didn't make sense, and I've changed it. I've also deleted this sentence: "The observation of neutrino oscillations also point towards proton decay being a real effect." Neutrino oscillation doesn't imply baryon number nonconservation; if there is some indirect, model-dependent link here, that needs to be explained.--Bcrowell 20:34, 23 Feb 2005 (UTC)

Another completely different hypothetical form of proton decay could be this one: I can imagine that an atomic nucleus with a distinct excess of protons over neutrons could decay by expelling one or more protons - and this would be called "proton decay", just as decay by expelling an electron is called "beta particle decay" or just "beta decay". However, this form of decay could be extraordinarily rare. Decay by expelling a positron might be a lot more likely. But just because a form of decay is rare doesn't mean that it is impossible. There are a few isotopes that decay, rarely, by expelling an entire carbon-12 nucleus -- but this has been observed in the laboratory.03:24, 11 August 2009 (UTC)

Such decays do exist. They are referred to as proton emission XinaNicole (talk) 06:23, 24 May 2011 (UTC)Reply

The article incorrectly assumes that decay into a neutral pion and a gamma is the only possible channel. If no assumptions are made on the decay mode, the experimental lower limit on proton mean life is just 1.6×10^25 years.

Source: Particle Data Group

—Herbee 2004-02-10

"it has been recently determined..." -- when? -- Tarquin 09:50, 16 Sep 2003 (UTC)

Proton decay is the conveniant hand wave that many theories use to explain certain components of background radiation. It is howveer highly unlikely. Neutrons decay because they are udd adn eventually both d will decay with the resulting electrons fighting over the only u, so one of them gets emitted. A proton however being uud does nto have that problem. —The preceding unsigned comment was added by AnthonyQBachler (talk • contribs) .

This article takes it as fact that there was an imbalance in the ratio of antimatter to matter in the early universe. I don't think there is any real experimental evidence of this. If so where is the article on it. I myself even have proposed an alternate theory for the matter-antimatter imbalance that does not require this magic.` 64.26.170.107 00:23, 28 Aug 2004 (UTC)

The article on it is at Baryogenesis. The reason why it has been proposed is because there is real evidence of it. As the temperature of the universe at the time of baryogenesis was higher than that required for pair production, particles would have been forming and annihilating constantly. An imbalance favoring the formation of matter over antimatter is the best explanation found to date for why there appears to be leftover matter in the universe. It may eventually be replaced with a different explanation, but any other explanation will have to be consistent with all of the observations that particle physics presently does such a good job of explaining. --Christopher Thomas 01:37, 8 December 2005 (UTC)Reply

To put it very simply, evidence can be inferred by calculating energy density of the cosmos either within a model that contains both matter and antimatter, or one that contains only one form of matter. Mathematical outcomes are different. As such, you can make assertions from a computer model. Of course, there's no evidence that the original inputs in the model are correct. (Dark matter and energy for instance, can be simply a matter of wrong starting inputs. Which I think they are, because very straight-forward logic tells me it's bogus. In fact, it's dangerously close to religuous beliefs which should be a tell-tale sign of itself.) Crusty007 (talk) 23:44, 25 February 2009 (UTC)Reply

There is a nice summary of baryogenesis and the matter-antimatter imbalance, but this article is about proton decay. The last sentence in the baryogenesis section essentially says: "and thus, proton decay." A little more explanation as to what proton decay has to do with the matter-antimatter asymmetry would be welcome for those of us for whom this seems to come out of left field. 99.48.75.121 (talk) 16:38, 7 February 2011 (UTC)Reply

If I'm reading the article on Sphalerons correctly, it is a theoretical possibility that remains unobserved - or so it seems to imply. So should this not be one of the possible proton decay modes, and thus appear BELOW the introduction? After all, the "normal" X boson mechanism is also assumed to be important only at high energies as well, so do sphalerons claim to explain the baron problem on their own, or not? Maury 20:56, 28 June 2006 (UTC)Reply

I don't know much about sphalerons, but it seems to me that the statement "the Standard Model does not predict proton decay" has to be stated with a caveat about sphalerons. I'm pretty sure that SM baryon number violation does not account for baryogenesis. We might vague-ify the wording in the introduction and move the sphaleron discussion further down into the technical details, but I'm not sure that would make things more clear. I'm more concerned about the technical bits at the bottom, which are pretty opaque even to me; and those pictures make my eyeballs very sad. -- Xerxes 21:43, 28 June 2006 (UTC)Reply

The proton is stable in the (pure) Standard Model; sphalerons only change the baryon number by 3. Maliz 14:16, 2 November 2006 (UTC)Reply

True. The proton is stable. But baryon number isn't conserved. You could have for instance a Deuteron decaying into an anti-proton (or some other anti-baryon) plus whatnot. Dauto (talk) 17:51, 8 February 2011 (UTC)Reply

"Diamonds are not forever" is a famous humorous phrase associated with the theory that protons might decay. Might be nice to find a reference and include that. —The preceding unsigned comment was added by DonPMitchell (talk • contribs) on 16:42, 11 February 2007.

I've moved the following recently-added passage from the article to the talk page:

Although proton would have so big half-life if it would decay, it is suggested that proton decay could be catalyzed by magnetic monopoles if their existence is possible.

I'd like to see references for this cited before it goes back in. I'm not saying it's _incorrect_; just that I hadn't heard of it, and everything in the article should be referenced anyways. --Christopher Thomas 21:16, 18 April 2007 (UTC)Reply

First, it is mentioned in Large Hadron Collider#Safety concerns, second it have reference, third google search shows many pages mentioning proton decay catalyzed by magnetic monopoles. --193.198.16.211 07:46, 19 April 2007 (UTC)Reply

It is mentioned in one paragraph in a 20-page document. While this is enough to establish that the idea exists, a suitable reference for your statement would be a link to a scientific paper whose primary topic was catalyzed decay of protons via monopoles. Please find one, so that the reference can be properly added.--Christopher Thomas 19:26, 19 April 2007 (UTC)Reply

Here is something more about magnetic monopoles and proton decay. --83.131.22.78 13:05, 20 April 2007 (UTC)Reply

I've added the link, and have tidied up the phrasing in that section. Thank you for finding the reference.--Christopher Thomas 20:21, 20 April 2007 (UTC)Reply

I was just watching Law & Order on DVD and looked up this article on a lark, so I added in the specific episode as a citation. --scooby

I thought that proton decay goes as follows: ${\displaystyle d->u+e^-+nubar_e}$ 

This is the way neutron decays into proton, electron and antineutrino. In proton decay two up quark decays into antidown antiquark and positron like this:

u + u -> X -> anti-d + e⁺ --83.131.64.38 14:00, 30 July 2007 (UTC)Reply

This section is WAY too technical for average reader. It was almost entirely written by Phys before two years (from 19:35, 19 September 2005 to 15:12, 10 October 2005 as it can be seen in history). There is no explaination in this section about what "decay operator" is or some wikilink about that term. There are some redlinks as well, and some links which aren't really helpful because they don't point to article which discuss the term in needed context. It's unlikely that anybody will find this section at the current state helpful, because those who understand it most probably already knows the contained information. This section needs an general rewrite to make it accessible to more general audience. --83.131.30.231 16:48, 21 July 2007 (UTC)Reply

Agreed; chunks of it are awful. E.g. there's no explanation of the dimension 4/5/6 stuff. Dreadful.--Michael C. Price ^talk 07:55, 7 October 2009 (UTC)Reply

Perhaps a reference should be added to the value of 10×10³⁵ years. The paper given (K. Hagiwara et al., "Particle Data Group current best estimates of proton lifetime", Phys. Rev. D 66, 010001 (2002) ISBN 978-06848657680) dates from 2002 and is presumably from the 2001 Super-Kamiokande results and gives > 10^31 to 10^33 years [d]

I couldn't find any results suggesting 10×10³⁵ years on the Super-Kamiokande website.

You will be aware that the average non-specialist reader will have seen 10×10³² years, or simply "10^33 years", and this is the value that other google sources bring up - from the same Super-Kamiokande experiment. e.g. the hyperphysics.phy-astr.gsu.edu site

"As of [2001], it seems that the proton lifetime has been pushed out to [at least] 10^33 years."

Excellent article, by the way Andysoh 22:28, 27 August 2007 (UTC)Reply

There's another reference which has been deleted, the rationale seems to be here--Robert Treat (talk) 05:52, 21 January 2009 (UTC)Reply

So, let's say---just hypothetically---that I---I mean someone---were to create a redirect page titled firstbit rotting, pointing to this page. Would that confuse people? Michael Hardy (talk) 06:02, 12 November 2008 (UTC)Reply

I can see where this might come from and am fairly amused by it, but I am also in a mind to send it to RfD as an implausible search term. ^_^ Double sharp (talk) 08:25, 10 July 2017 (UTC)Reply

Could the annihilation of matter/anti-matter collisions be a precursor to the creation of "Dark Matter" and/or "Dark Energy"?

Just a thought that popped into my head just now.

KJI (talk) SR (talk) 20:30, 27 November 2008 (UTC)Reply

The way I figure, when the big bang occurred there must have been segments of matter created and segments of anti-matter, and these immediately flew apart before annihilating each other. We happen to live in a region of matter. Maybe there is still some contact between matter and antimatter regions that could account for the dark energy. I've also speculated the Milky Way's movement relative to Andromeda, the Virgo Cluster and the Great Attractor might be influencing readings--Robert Treat (talk) 05:44, 21 January 2009 (UTC).Reply

In the baryogenesis section of the article, a reference is made to the Higgs boson and the article used the symbol "T", which I have replaced with
H⁰
. Later in the article, references are made to a "Higgs triplet" with symbol "T" and "T". Maybe both should reference the triplet? I don't know - please respond if you do and update the page if needed. I have not education in physics and do not know what this Higgs triplet is. The article is not clear about this either. Maybe someone can add a bit more context/clarification or better references?

Thanks!     — SkyLined (talk) 10:48, 26 October 2010 (UTC)Reply

Proton decay#Dimension-5 proton decay operators mentions something called a "tripletino". It's a red link, and has been since it was added in 2005. A full-text search of the arXiv for this word turned up exactly one paper. Obviously the word is not in common use among physicists and should be removed, but I don't know what should replace it. -- BenRG (talk) 07:06, 24 April 2011 (UTC)Reply

One of the authors, Jihn E. Kim, is very active in the field. I suggest we just ask him. This is a more recent paper, also submitted by him. Count Iblis (talk) 14:52, 24 April 2011 (UTC)Reply

Although the phenomenon is referred to as "proton decay", the effect would also be seen in neutrons bound inside atomic nuclei. Free neutrons—those not inside an atomic nucleus—are already known to decay into protons (and an electron and an antineutrino) in a process called beta decay. Free neutrons have a half-life of about 10 minutes (613.9±0.8 s)[6] due to the weak interaction. Neutrons bound inside a nucleus have an immensely longer half-life

Does this mean neutrons can decay in a manner similar to protons (assuming proton decay happens at all)? Or does it mean indirectly, in that neutrons decay into protons which then undergo proton decay? If the protons in a nucleus were to decay, you'd end up, in some cases, with nuclides that would undergo beta-minus decay until eventually a nuclide was reduced to ²H which would then undergo proton decay ending up with a free neutron, which would decay into a proton and eventually itself decay XinaNicole (talk) 06:36, 24 May 2011 (UTC)Reply

Neutrons like protons are made of three quarks and can directly decay (for instance into a positron plus a pion) assuming that baryon number conservation can be violated. Dauto (talk) 13:46, 24 May 2011 (UTC)Reply

What would the neutron decay path be? Would it be something like n -> e⁺ + π^-? And is its half-life expected to be similar to that of a proton? XinaNicole (talk) 08:56, 17 June 2011 (UTC)Reply

Now that the higgs boson has been discovered, why don't they use the higgs boson to attempt to decay protons? Malamockq (talk) 14:32, 4 July 2015 (UTC)Reply

The citation given in the article for a theoretical upper bound of 6 × 10³⁹ years for the mean lifetime of the proton is in turn cited from another source: http://www.arxiv.org/pdf/hep-ph/0410198v4.pdf . However, both papers give the upper bound not as a calculated result, but as the unsolved result of an equation proportional to both the X-boson rest mass-energy (m_X ≥ √[α_GUT]∙[4.3 × 10¹⁴ GeV/c²]) and the strength of the GUT force (α_GUT). Since those figures are not precisely defined, should the upper-bound figure in years be removed from the article? I would suggest simply modifying the article statement to something like "there may be a theoretical upper bound to the lifetime of the proton" (keeping the same citation given), rather than trying to give a precise figure. Also, any mean lifetimes of the proton should be multiplied by ln(2) to be consistent with the other figures, which are given as half-lives instead of mean lifetimes. Nicole Sharp (talk) 12:46, 30 August 2016 (UTC)Reply

I'm not very familier with the spectrum of different GUT theories such as those given in the Proton decay#Projected proton lifetimes section. Be good to know how those theories sort by these predictions. Jason Quinn (talk) 18:15, 9 December 2016 (UTC)Reply

“The universe, as a whole, seems to have a nonzero positive baryon number density – that is, matter exists.” I think the aside”..that is, matter exists “ is well intentioned, it’s saying the universe would be much different and we wouldn’t be here, but is it strictly true?Rich (talk) 23:17, 12 January 2020 (UTC)Reply

So, considering no proton decay has been found to happen, and the theory of sudden expansion or 'Big Bang' predicts that protons should decay - this necessarily puts the Big Bang Theory into question, does it not? I'm far from an expert, but if this is the case, shouldn't it be mentioned in the article? --82.21.97.70 (talk) 15:38, 13 July 2020 (UTC)Reply

Your "if" doesn't work because the Big Bang doesn't require proton decay. Certain models of it include proton decay, but that is not the same thing. IAmNitpicking (talk) 19:05, 13 July 2020 (UTC)Reply

Fair enough. I wasn't aware there were necessarily more than one model of the 'Big Bang'. I thought it was just one, with some conjecture as to whether or not the universe would continue expanding, or a 'Big Crunch', or reach equilibrium. I guess 'Superstring' theory is also a variational addition to the model..? However, if proton decay is indeed a part of one of the Big Bang models, shouldn't that be mentioned in the article? --82.21.97.70 (talk) 19:05, 27 July 2020 (UTC)Reply

Proton decay has been observed and published. 2600:4041:66B7:4D00:1541:BAFD:CE58:D24B (talk) 21:31, 18 August 2023 (UTC)Reply

What is this? Cannot find it in Google search 2607:FEA8:FF01:47D8:3D09:96CC:BBE9:923F (talk) 00:35, 20 June 2023 (UTC)Reply

Proton decay has been observed. Numerous countries have independently observed it.keep looking for other published articles stating the findings. 2600:4041:66B7:4D00:1541:BAFD:CE58:D24B (talk) 21:28, 18 August 2023 (UTC)Reply