Large Supersymmetric Contribution to CP Asymmetry of B_d to φ K_S from Left-Handed Squark Mixing

Supersymmetric contribution to the CP asymmetry of B_d \to \phi K_S is re-examined. It is emphasized that our analysis takes into account the recently found constraint from the mercury electric dipole moment, in addition to the well-known constraint from the branching ratio of b \to s \gamma. We show that, despite these constraints, the CP asymmetry can considerably deviate from the Standard Model prediction, if the CP-odd flavor mixing comes from left-handed squarks. Alignment mechanism of sfermion masses and mixing may imprint the required flavor mixing at high energy scale.