Talk:Proton decay

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[edit] Article phrasing concerns

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)

[edit] Proton decay modes

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

[edit] Specific date and citation requested

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

[edit] Proton decay objection

Proton decay is the conveniant hadn wave that many theories use to explain certain components of background radiation. I tis 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) .

[edit] Imbalance of matter and antimatter

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 is 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 favouring 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)

[edit] Is the sphaleron mention OK?

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)

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

[edit] Quote

"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.

[edit] Reference needed

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)

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)
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)

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

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)

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

[edit] The down quark decays into an up quark

I thought that proton decay goes as follows: d − > u + e < sup > − < / sup > + nubar < sub > e < / sub >

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)

[edit] Decay operators

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)

[edit] Experimental evidence - reference would be good

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)