Precision Measurements of B Meson Decays and Search for Supersymmetry

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1)We have searched for physics beyond the Standard Model based on precision measurements of CP violation in B meson system. The B to phi Ks decay is induced by a quantum loop (a.k.a. penguin) process, where New Physics can contribute. CP asymmetry measured in B to phi Ks, therefore, can be different from that in B to J/psi Ks, where only the tree Standard Model process dominates. Based on 152 million B anti-B pairs observed by Belle detector, we have determined CP asymmetry for B to phi Ks to be S=-0.96+-0.52, which is somewhat disagreement with CP asymmetry for B to J/psi Ks, S=+0.733+-0.057+-0.028. We must further improve the statistical accuracy of this measurement to see if this potential discrepancy remains true.2)We have observed large CP violation in B to pi+pi- decay using 152B anti-B pairs, for the first time.3)We have measured, for the first time, the inclusive branching faction of Flavor Changing Neutral Currents process, b to s l+l-, where l can be an electron or a muon. We determined Br(b to sl+l-) to be (4.39+-0.84+0.78-0.73) x 10-6. This measurement can be used to constrain many New Physics models including Supersymmetric model.