Benchmarks for the new-physics search through CP violation in B0 → π0KS

Using isospin relations, we predict the standard model correlation between S K-0(pi)S equivalent to (sin2 beta)(pi)K-0(S) and A(pi)(0)K(S), the mixing-induced and direct CP asymmetries of B-0 -> pi K-0(S). The calculation uses flavor SU(3) only to fix the isospin-3/2 amplitude through the B-+/- -> pi(+/-)pi(0) branching ratio, and thus has a small irreducible theoretical error. It can reach percent level precision thanks to expected future lattice-QCD progress for the calculation of the relevant SU(3)-breaking form-factor ratio, and serves as a benchmark for new-physics searches. We obtain an interesting picture in the A(pi)(0)K(S)-(S pi KS)-K-0 plane, where the current experimental data show a discrepancy with the standard model, and comment on the direct CP asymmetries of B-0 -> pi K--(+) and B+ -> pi K-0(+). A modified electroweak penguin with a large new CP-violating phase can explain the discrepancy and allows us to accommodate also the corresponding data for other b -> s penguin-dominated decays.