Towards New Frontiers with $B\to\pi K$ Decays

TL;DR

This paper investigates anomalies in $B\to\pi K$ decays, suggesting potential New Physics involving modified electroweak penguins and $Z'$ bosons, with strategies to test these ideas at Belle II.

Contribution

It uncovers new tensions with the Standard Model in $B\to\pi K$ decays and proposes a novel approach to identify underlying New Physics scenarios.

Findings

Identified tensions with the Standard Model in CP asymmetries.

Proposed a new strategy to detect New Physics effects.

Discussed the potential of Belle II to test these ideas.

Abstract

Exploring correlations between the CP asymmetries of $B^0_d\to\pi^0K_{\rm S}$ following from an isospin relation, we uncover new tensions with the Standard Model in data for neutral $B\to\pi K$ decays. Should this intriguing picture originate from New Physics, a modified electroweak penguin sector provides a key scenario. It includes models with extra $Z'$ bosons, which offer attractive ways to resolve anomalies in $B\to K^{(*)}\ell^+\ell^-$ measurements. We present a new strategy to reveal the underlying physics, apply it to current $B\to\pi K$ data, and discuss the excellent prospects for Belle II.