When top quarks and their anti-particles, anti-top quarks, are created in particle collisions at the Tevatron, detectors note the direction in which they fly. Theory predicts that the particles will favor one direction slightly over the other, traveling that way about 5 percent of the time more.
However, in studies by the DZero collaboration and the CDF collaboration, the particles seemed to be picky 15 percent of the time. Top quarks went forward and anti-top quarks went backward. This month, the CDF collaboration announced results with an even larger asymmetry.
This could possibly be quite exciting. More confirmation of this should come later this summer, and especially from the LHC that should be able to verify this, if it truly exists.