Benchmarks for the New-Physics Search through CP Violation in B^0->pi^0 K_S
Abstract
Using isospin relations, we predict the Standard-Model correlation between S_{pi^0 K_S}=(sin 2beta)_{pi^0 K_S} and A_{pi^0 K_S}, the mixing-induced and direct CP asymmetries of B^0-> pi^0 K_S. The calculation uses flavour SU(3) only to fix the isospin-3/2 amplitude through the B^\pm->pi^\pm 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^0 K_S} 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^0 K^+. 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.
Cite
@article{arxiv.0806.2900,
title = {Benchmarks for the New-Physics Search through CP Violation in B^0->pi^0 K_S},
author = {Robert Fleischer and Sebastian Jager and Dan Pirjol and Jure Zupan},
journal= {arXiv preprint arXiv:0806.2900},
year = {2008}
}
Comments
4+1 pages, 7 figures, update to ICHEP08 data, to appear as Rapid Communication in Physical Review D