Flavour Anomalies

TL;DR

This paper reviews current flavour anomalies in B-meson decays and other processes, discussing their potential interpretations within a model-independent framework and summarizing recent experimental and theoretical developments.

Contribution

It provides a comprehensive overview of flavour anomalies, including recent experimental discrepancies and possible model-independent explanations, along with insights into other related flavour phenomena.

Findings

Discrepancies in $b\to c\tau\bar\nu_\tau$ and $b\to s\ell^+\ell^-$ transitions

Standard Model predictions align with measurements for $\varepsilon_K'/\varepsilon_K$

Discussion of alternative flavour anomalies like CP asymmetry in $D^0$ decays

Abstract

The experimental data on $b\to c\tau\bar\nu_\tau$ and $b\to s\ell^+\ell^-$ transitions exhibit sizeable discrepancies with the Standard Model expectations. We present an overview of the present status and discuss possible interpretations within a model-independent effective Lagrangian approach. We also briefly elaborate on some other claimed flavour anomalies such as the recently observed CP asymmetry in $D^0$ decays or the $K^0\to \pi\pi$ ratio $\varepsilon_K'/\varepsilon^{\phantom{'}}_K$. The Standard Model prediction for the direct $CP$-violating ratio $\varepsilon_K'/\varepsilon^{\phantom{'}}_K$ agrees with its measured value, once all theoretical ingredients are correctly taken into account.