Possible complex annihilation and B -> K pi direct CP asymmetry

TL;DR

This paper demonstrates that penguin annihilation in soft-collinear effective theory can generate a significant strong phase, explaining observed direct CP asymmetries in B meson decays and reconciling different theoretical approaches.

Contribution

It shows that including small scale suppressed terms in the denominators of propagators produces a strong phase consistent with experimental data, resolving previous theoretical discrepancies.

Findings

Strong phase from penguin annihilation can explain CP asymmetry data.

Reconciles soft-collinear effective theory with perturbative QCD results.

Provides a theoretical framework for direct CP asymmetry in B decays.

Abstract

We point out that a sizable strong phase could be generated from the penguin annihilation in the soft-collinear effective theory for B meson decays. Keeping a small scale suppressed by O(Lambda/m_b), Lambda being a hadronic scale and m_b the b quark mass, in the denominators of internal particle propagators without expansion, the resultant strong phase can accommodate the data of the B^0 -> K^-+ pi^+- direct CP asymmetry. Our study reconciles the opposite conclusions on the real or complex penguin annihilation amplitude drawn in the soft-collinear effective theory and in the perturbative QCD approach based on k_T factorization theorem.