Some results on Lepton Flavour Universality Violation

TL;DR

This paper investigates potential New Physics explanations for Lepton Flavour Universality violations observed in recent experiments, using effective Lagrangian methods and specific models, with a focus on complex Wilson coefficients.

Contribution

It introduces an analysis of complex Wilson coefficients in B-anomaly fits within Z' and S_3 leptoquark models, improving the global fit and predictions.

Findings

Complex couplings slightly improve the global fit.

Inclusion of complex Wilson coefficients marginally enhances elta Ms predictions.

Analysis supports potential New Physics contributions to Lepton Flavour Universality violations.

Abstract

Motivated by recent experimental measurements on flavour physics, in tension with Standard Model predictions, we perform an updated analysis of New Physics violating Lepton Flavour Universality, by using the effective Lagrangian approach and in the Z' and S_3 leptoquark models. We explicitly analyze the impact of considering complex Wilson coefficients in the analysis of B-anomalies, by performing a global fit of R_K and R_K*0 observables, together with \Delta Ms and A_CP^mix. The inclusion of complex couplings provides a slightly improved global fit, and a marginally improved \Delta Ms prediction.