Search for Direct CP Violation in B -> K pi Decays

TL;DR

This study searches for direct CP violation in B -> K pi decays by measuring rate asymmetries using data from the Belle experiment, finding no significant CP violation within the measured confidence intervals.

Contribution

First measurement of direct CP violation asymmetries in B -> K pi decays using a large data sample from Belle at KEKB.

Findings

Measured CP asymmetry intervals for various decay modes.

No significant evidence of direct CP violation found.

Combined analysis constrains asymmetry to within ±0.25 at 90% CL.

Abstract

We search for direct CP violation in flavor specific B -> K pi decays by measuring the rate asymmetry between charge conjugate modes. The search is performed on a data sample of 11.1 million B B bar events recorded on the Upsilon(4S) resonance by the Belle experiment at KEKB. We measure 90% confidence intervals in the partial rate asymmetry A_CP of -0.25 < A_CP(K-/+ pi+/-) < 0.37, -0.40 < A_CP(K-/+ pi^0) < 0.36, and -0.53 < A_CP(K^0 pi-/+) < 0.82. By combining the K-/+ pi+/- and K-/+ pi^0 final states, we conclude that -0.22 < A_CP[K-/+(pi+/- + pi^0)] < 0.25 at the 90% confidence level.