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The Nobel Prize in Physics in 1980 was awarded to James Cronin and Val Fitch for their discovery of a violation of Charge and Parity Invariance, in which the neutral kaon's quarks change into their corresponding antiquarks, and vice-versa. However, the vice-versa does not occur with the same probability and shows a reason for the matter-antimatter imbalance in the universe.

Every article nowadays in magazines and websites seems to say that there has been no observed asymmetry between matter and antimatter, except there was already a Nobel Prize awarded for one such observation.

Why is this violation of CP invariance not sufficient enough for certain researchers and articles to describe the dominance of matter over antimatter? Wouldn't this imbalance in the nature of quarks and antiquarks be extremely important and consequential in the moments after the Big Bang, especially in the moments where the universe was a quark-gluon plasma?

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I think this a result mostly of two factors: general substandard quality of popsci articles and second that we still don't really understand CP violation that well (there's e.g. the strong CP problem). So, the fact that it has been observed (and by now it has been well observed in the B meson experiments) doesn't really imply that there's nothing left to study... –  Marek Jun 23 '11 at 19:37
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1) Does antimatter-matter symmetry exist? Yes there is a CP violation and the whole Nobel prize thing. On the other hand there is CPT symmetry which is very protected. So call it what you want. As for the popsci articles... I would express my thoughts, but this is a family site.

2)Does CP violation explain matter-antimatter imbalance? It's certainly necessary for this to happen. You also need to violate Baryon number (the number of quarks minus the number of antiquarks) and you need to be out of thermal equilibrium. You can engineer all these things within the Standard Model plus inflationary cosmology, but I think you get an imbalance which is way too tiny. Like only one part in a trillion. So the whole thing is still an ongoing research problem.

I'll try to find you a decent reference article.

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+1 for "..this is a family site." Haha –  qftme Jun 24 '11 at 11:46
    
Try arxiv.org/abs/1206.2942 for a recent review of the subject. The focus of that article is on electroweak baryogenesis. There are other important scenarios, such as leptogenesis, but in all cases beyond standard model physics is required quantitatively. The SM has all the right qualitative ingredients for baryogenesis, but the numbers just don't work out for two main reasons. First: the Higgs is too heavy (50 GeV lighter and there might have been a chance). Second: The CP violating phase in the CKM matrix is too small to generate the necessary imbalance in time to beat washout. –  Michael Brown Feb 9 '13 at 0:44
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