Talk:CP-violation
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[edit] Hyphenation
Why is this term hyphenated? Surely as a noun, "CP violation" should not be hyphenated. As an adjective "CP-violating" should be. The same of course applies to "T violation", "CPT violation" etc. Does an expert in English language want to comment? Paulfharrison 07:57, 29 May 2007 (UTC). Note that none of the section headings has "CP violation" hyphenated, and neither do the books of the same title in the references at the bottom.Paulfharrison 08:54, 30 May 2007 (UTC)
- You are entirely correct; the hyphen, and the one in "CP symmetry", are unnecessary. Can someone move this? 91.107.176.199 (talk) 01:03, 29 February 2008 (UTC)
[edit] Terminology?
'CP-symmetry was violated and only a much stronger version of the symmetry existed, CPT-symmetry'
- Is this correct terminology? I would say that if some symmetry is violated a stronger one is also violated (a strong condition or property implies a weaker one). I would say that CPT-symmetry is neither stronger nor weaker than CP-symmetry (CPT-symmetry would however be weaker than CP- and T-symmetry together). Patrick 12:11 Nov 24, 2002 (UTC)
- I understand now that 'strong version' in this context means 'more universally true'. Some clarification in the articles would be useful, as what in logic would be a weak condition/property would be strong in this sense. Patrick 13:02 Nov 24, 2002 (UTC)
- Cleaned up by Voyajer 12/2/05
[edit] To merge "Strong CP problem" here
- I say yes, it is better to handle a thing at one place, and 'Strong CP problem" is a stub anyway. Also, CP-symmetry is redirected to here, it makes even more sense. Hidaspal 19:02, 28 April 2006 (UTC)
- Done. Hidaspal 20:39, 28 April 2006 (UTC)
OK, well, don't go to crazy merging. Someday, someone might want to write a long article for the strong CP problem, and there won't be room for that here. But whatever, this was not a bad choice. linas 05:38, 29 April 2006 (UTC)
- In fact, there should be a long article on the strong CP problem. There's really no excuse other than laziness for it not existing right now. On a related note, tho, the name of this article should really be CP-symmetry, not CP-violation, to match all the other symmetries in the CPT family. -- Xerxes 19:24, 29 April 2006 (UTC)
[edit] Relation to standard model
I just edited this, see [1]. Since I'm not a physicist, someone should probably check me. Especially the bit where I link to Planck Mass is shaky. I think it's meaningful (why is CP violation relatively livelier on the experimental side, when theorists wouldn't a priori focus there to extend the Standard Model?) but clearly leaping over the Higgs mass to the Planck mass is a giant step. If someone knows an honest way not to make that leap then please fix it. --Homunq 11:53, 13 August 2006 (UTC)
[edit] Matter vs. Anti matter?
- The Standard Model contains only two ways to break CP symmetry. The first of these, discussed above, is the QCD lagrangian; but one would expect this to lead to either no CP violation or a CP violation that is many, many orders of magnitude too large. The second of these, involving the weak force, can account for a small portion of CP-violation, but it is predicted to be sufficient for a net mass of matter equivalent to only a single galaxy in the known universe.
What about mass of neutrinos? Since they change type, they experience time, and so have mass; since they are their own anti-particle, this is a way for equal amounts of particle and anti-particle to have mass. Or am I completely off base? Keybounce 06:45, 14 November 2006 (UTC)
- I'm no expert, but I changed the article to say "normal matter" because you may be right. Of course, the phrase "net matter" could be interpreted to mean "matter minus antimatter" which would exclude particles like neutrinos. --Homunq 15:37, 14 November 2006 (UTC)
[edit] Axions
I'm not a physicist, physics student, or that "up" on physics news for the most part... But I saw that recently some evidence for the existnce of axions seems to have come out. Can one of you more knowledgeable types take a better look at it and see what relevance it might have to this article? http://www.physorg.com/news84633896.html 130.15.164.44 22:52, 6 December 2006 (UTC)
This is mentioned on the Axion page.
[edit] Myther et al
No person called Myther is known to the physics preprint archive or to NASA ADS. I assume the following (inserted recently by 203.188.168.30) is OR or a hoax of some sort, so removed it:
- Myther et al suggest that, if T-symmetry is violated, then there could be a possibility of the universe experiencing a big crunch without going through a complete replay of the history of universe. Thus, the problems associated with the reversed arrow of time posed by the laws of thermodynamics can be ignored assuming that the universe will then start experiencing a different history while moving towards the big crunch from a distinct point in future when the universe will cease to expand and gravity will take over.
(The same user inserted another reference to this under Aeon). PaddyLeahy 00:26, 27 April 2007 (UTC)
[edit] QCD Lagrangian
I see in the Strong CP Problem section, the Lagrangian has terms like
It's a picky point, and possibly beyond my knowledge, but what does the trace even mean here? As far as I'm concerned, FμνFμν is a trace of sorts. There are certainly no clear free indices left over which to sum. The tr seems redundant and, more importantly, inconsistent with other articles. Warrickball (talk) 20:54, 21 May 2008 (UTC)
