Direct $CP$ violation from isospin symmetry breaking effects in PQCD

TL;DR

This paper studies how tiny isospin symmetry breaking effects, from electroweak interactions and quark mass differences, can significantly influence direct CP violation in certain B meson decays within the PQCD framework.

Contribution

It demonstrates that leading order isospin symmetry breaking effects can notably alter CP violation predictions by introducing new strong phases.

Findings

Isospin breaking effects impact CP violation in B decays.

Electroweak and quark mass differences contribute to symmetry breaking.

Leading order effects can shift CP violation due to new strong phases.

Abstract

We investigate the direct $CP$ violation for the decay process of $\bar{B}_{s}\rightarrow P(V)\pi^{0}$ (P,V refer to the pseudoscalar meson and vector meson, respectively) via isospin symmetry breaking effects from the $\pi^{0}-\eta-\eta'$ mixing mechanism in PQCD factorization approach. Isospin symmetry breaking arises from the electroweak interaction and the u-d quark mass difference by the strong interaction which are known to be tiny. However, we find that isospin symmetry breaking at the leading order shifts the $CP$ violation due to the new strong phases.