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I'm looking for the most readable quantitative explanation, with the least amount of difficult mathematics. Rather than an answer with just a number, I'd like to see the derivation from the CKM matrix.

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Surprisingly, Matt provided you with an answer - an "invariant" - but I find your question bizarre. How can one define "how much CP violation there is"? It depends on the experiment, doesn't it? Some phenomena are strongly affected by it, others are virtually unaffected. You didn't specify any experiment so I don't think that your question as stated makes any sense. Of course that those effects that are CP-violating will have a good quantification in terms of $Prof(E)/Prob(E_{CP})-1$, and this result will ideally start at $\delta_{CKM}^2$. – Luboš Motl Feb 10 '11 at 7:12
Please feel free to rewrite the question; I'm looking for a simple derivation of the Jarlskog invariant J_CP and wanted to phrase the question so people not knowing that term would still find the question in a search. – Carl Brannen Feb 10 '11 at 9:29
up vote 4 down vote accepted

A clear recent review of flavor physics, including CP violation, is in the TASI lectures by Gedalia & Perez. The parametrization-independent measure of how much CP violation is present in the Standard Model is called the "Jarlskog invariant"; it's explained in those lectures, but might be a useful keyword if you're searching for other resources. If you want to understand why the observed CP violation is insufficient to explain the baryon asymmetry we observe in the universe around us, you might try these lectures on baryogenesis by Jim Cline.

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No, I was looking for an explanation of why the Jarlskog invariants are important. The nice review article covers massive territory beyond that. And the referenced Jarlskog article costs $34. – Carl Brannen Feb 10 '11 at 9:21
@Carl Brannen: try the KEK scan of the Jarlskog paper linked from Spires,C29,491 – Matt Reece Feb 10 '11 at 16:21
much appreciated and not very simple. – Carl Brannen Feb 10 '11 at 18:49

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