Lepton Flavor Violation in Semileptonic Observables

TL;DR

This paper provides a comprehensive analysis of lepton flavor violation in semileptonic processes within an effective field theory framework, emphasizing the importance of loop effects and RGEs in constraining new physics models.

Contribution

It introduces a detailed RGE-based approach to study LFV in semileptonic transitions, including correlations between processes and updated meson decay expressions.

Findings

Loop effects significantly improve bounds on LFV coefficients.

Correlations between different LFV processes are elucidated.

Expressions for semileptonic LFV meson decays are provided.

Abstract

In this paper, we perform a comprehensive study of Lepton Flavor Violation (LFV) in semileptonic transitions in the framework of an Effective Field Theory with general flavor structure. We account for the Renormalization Group Equations (RGEs), which induce non-trivial correlations between the different types of LFV processes. In particular, we show that these loop effects are needed to improve the bounds on several coefficients that are not efficiently constrained at tree level. For illustration, we consider a few concrete scenarios, with predominant couplings to third-generation quarks, and we explore the correlations between the various tree- and loop-level constraints on these models. As a by-product, we also provide expressions for several semileptonic LFV meson decays by using the latest determinations of the relevant hadronic form factors on the lattice.