Examination of Flavor Symmetry in $B, B_s \to K \pi$ Decays

TL;DR

This paper investigates the flavor symmetry in B meson decays to K pi modes, revealing significant SU(3) symmetry breaking and questioning the validity of factorization assumptions based on current experimental data.

Contribution

It analyzes the relation between the weak phase gamma and decay rates, highlighting the impact of measurements on understanding SU(3) symmetry and factorization in B decays.

Findings

Large SU(3) breaking in strong phases

Failure of factorization in B0 and Bs K pi modes

Branching ratio for Bs → K- pi+ must be higher for symmetry validity

Abstract

We study a relation between the weak phase $\gamma$ and the rates and CP asymmetries of several $K \pi$ decays of $B^+$, $B^0$, and $B_s$, emphasizing the impact of the latter measurements. Current data indicate large SU(3) breaking in the strong phases or failure of factorization (including its application to penguin amplitudes) in $K \pi$ modes of $B^0$ and $B_s$. SU(3) and factorization only remain approximately valid if the branching ratio for $B_s \to K^- \pi^+$ exceeds its current value of $(5.27 \pm 1.17) \times 10^{-6}$ by at least 42%, or if a parameter $\xi$ describing ratios of form factors and decay constants is shifted from its nominal value by more than twice its estimated error.