A precise sum rule among four B→Kπ CP asymmetries

A sum rule relation is proposed for direct CP asymmetries in B→Kπ decays. Leading terms are identical in the isospin symmetry limit, while subleading terms are equal in the flavor SU(3) and heavy quark limits. The sum rule predicts ACP(B0→K0π0)=−0.17±0.06 using current asymmetry measurements for the other three B→Kπ decays. A violation of the sum rule would be evidence for new physics in b→sq¯q transitions.