# Quark masses, CKM angles and Lepton Flavour Universality violation

## TL;DR

This paper explores how a broken $U(2)$ flavour symmetry can explain quark mass ratios, CKM angles, and potential anomalies in B-decays via vector leptoquark exchange, linking flavour physics and new physics signals.

## Contribution

It introduces two $U(2)$-models that connect flavour symmetry breaking to observed anomalies in B-decays through vector leptoquark interactions.

## Key findings

- Successful relations between quark masses and CKM angles.
- Models predict observable Lepton Flavour Universality violation.
- Potential explanation for current B-decay anomalies.

## Abstract

A properly defined and suitably broken $U(2)$ flavour symmetry leads to successful quantitative relations between quark mass ratios and CKM angles. At the same time the intrinsic distinction introduced by $U(2)$ between the third and the first two families of quarks and leptons may support anomalies in charged and neutral current semi-leptonic $B$-decays of the kind tentatively observed in current flavour experiments. We show how this is possible by the exchange of the $(3,1)_{2/3}$ vector leptoquark in two $U(2)$-models with significantly different values of Lepton Flavour Universality violation, observable in foreseen experiments.