Recent Measurements of CP Asymmetries of B \to \phi K^0 and B \to \eta'   K_S at B-factories Suggest New CP Violation in Left-Handed Squark Mixing
  Recent results on the mixing-induced CP asymmetries of B \to \phi K^0 and B \to \eta' K_S measured at B-factories appear to indicate discrepancies from the Standard Model expectation. Explanation of this possible anomaly is given in the context of supersymmetric extension of the Standard Model. It is shown that the present data, if the average of two experiments is taken, implies additional CP violation appearing in the generation mixing of left-handed squarks rather than that of right-handed ones. This explanation is argued to disfavor many mediation mechanisms of supersymmetry breaking, including minimal supergravity, because renormalization group effects via Yukawa interaction are unlikely to generate the desired mass mixing. 
Motoi Endo, Satoshi Mishima and Masahiro Yamaguchi