Ju n 20 01 BELLE KEK Preprint 2001-34 Belle Preprint 2001-9 Search for Direct CP Violation in B → Kπ Decays ∗ ( The Belle Collaboration )

We search for direct CP violation in flavor specific B → Kπ decays by measuring the rate asymmetry between charge conjugate modes. The search is performed on a data sample of 11.1 million BB̄ events recorded on the Υ(4S) resonance by the Belle experiment at KEKB. We measure 90% confidence intervals in the partial rate asymmetry ACP of −0.25 < ACP(Kπ) < 0.37, −0.40 < ACP(Kπ) < 0.36, and −0.53 < ACP(Kπ) < 0.82. By combining the Kπ and Kπ final states, we conclude that −0.22 < ACP(K(π + π)) < 0.25 at the 90% confidence level. Typeset using REVTEX