# B-physics anomalies: a guide to combined explanations

## TL;DR

This paper explores how New Physics, especially third-generation couplings, can explain B-physics anomalies and Lepton Flavour Universality violation using an EFT approach and simplified models.

## Contribution

It provides a unified EFT framework for B-physics anomalies and demonstrates how to reconcile these with experimental constraints using specific flavor symmetries.

## Key findings

- A natural parameter choice addresses electroweak and search constraints.
- Simplified models with TeV-scale mediators can explain anomalies.
- An $SU(2)_L$-singlet vector leptoquark is a particularly effective solution.

## Abstract

Motivated by additional experimental hints of Lepton Flavour Universality violation in B decays, both in charged- and in neutral-current processes, we analyse the ingredients necessary to provide a combined description of these phenomena. By means of an Effective Field Theory (EFT) approach, based on the hypothesis of New Physics coupled predominantly to the third generation of left-handed quarks and leptons, we show how this is possible. We demonstrate, in particular, how to solve the problems posed by electroweak precision tests and direct searches with a rather natural choice of model parameters, within the context of a $U(2)_q \times U(2)_\ell$ flavour symmetry. We further exemplify the general EFT findings by means of simplified models with explicit mediators in the TeV range: coloured scalar or vector leptoquarks and colour-less vectors. Among these, the case of an $SU(2)_L$-singlet vector leptoquark emerges as a particularly simple and successful framework.