New Physics Search in the Doubly Weak Decay $\overline B^0 \to K^+ \pi^- $

TL;DR

This paper investigates the rare doubly weak decay $ar{B}^0 o K^+ o ar{ ext{pion}}$ as a potential signal for new physics beyond the Standard Model, analyzing possible enhancements in decay rates within various models.

Contribution

It provides a model-independent analysis of the decay using effective operators and explores significant new physics effects in Randall-Sundrum models, suggesting experimental searches at LHCb and Belle-II.

Findings

Large potential enhancements in decay rate within new physics models.

Decay could be observable in future experiments.

Analysis covers both model-independent and specific Randall-Sundrum scenarios.

Abstract

The doubly weak transition $b\to dd{\bar s}$ is highly suppressed in the standard model, which makes it a potential channel to explore new physics signals. We present a study of the exclusive two body wrong sign weak decay $\smash{\overline B}^0\to K^+\pi^-$ belonging to this class within the perturbative QCD approach. We perform a model independent analysis for various effective dimension-6 operators, in which large effects are possible. We further analyze the considered process in example models such as Randall-Sundrum model, including the custodially protected and the bulk-Higgs Randall-Sundrum model. Exploring the experimentally favored parameter spaces of these models leads to a large and significant enhancement of the decay rate, compared to the standard model result, which might be accessible in future experiments. We propose to look for the wrong sign decay $\smash{\overline B}^0\to K^+\pi^-$ via flavour-tagged time-dependent analyses, which can be performed at LHCb and Belle-II.