Non-minimal $331$ model for Lepton Flavour Universality Violation in $b\to s\ell\ell$ decays

TL;DR

This paper explores a non-minimal 331 extension of the Standard Model that can account for lepton flavour universality violation observed in B-meson decays without causing lepton flavour violation, aligning with recent LHCb results.

Contribution

It introduces a non-minimal 331 model capable of explaining lepton universality violation in $b o s\,\ell\ell$ decays without lepton flavour violation, expanding the theoretical framework.

Findings

The model can embed lepton universality violation consistent with LHCb data.

It accommodates favored New Physics scenarios in $b\to s\ell\ell$ processes.

Phenomenological constraints are considered for the model's viability.

Abstract

331 models constitute an extension of the Standard Model (SM) obtained by enlarging the SM gauge group $SU(3)_\text{C}\times SU(2)_\text{L}\times U(1)_Y$ to the group $SU(3)_\text{C}\times SU(3)_\text{L}\times U(1)_X$. We investigate how a non-minimal 331 model may embed lepton flavour universality violating contributions to $b\to s\ell\ell$ processes without introducing lepton flavour violation, as suggested by the recent LHCb measurements of the ratios $R_K$ and $R_{K^*}$. We discuss the model-independent scenarios of New Physics in $b\to s\ell\ell$ currently favoured by the data that could be accommodated by this model and consider a few phenomenological constraints on this model.