Light Leptonic New Physics at the Precision Frontier

TL;DR

This paper examines how precision leptonic observables can indicate either short-distance or long-distance new physics, highlighting the role of inverse see-saw models in interpreting these signals within current experimental sensitivities.

Contribution

It identifies which leptonic precision observables can be explained by light new physics models like inverse see-saw, clarifying their interpretative scope at the electroweak scale.

Findings

Inverse see-saw models can explain lepton universality violations.

Most leptonic observables can be interpreted via light new physics.

Electron EDM remains incompatible with light new physics explanations.

Abstract

Precision probes of new physics are often interpreted through their indirect sensitivity to short-distance scales. In this proceedings contribution, we focus on the question of which precision observables, at current sensitivity levels, allow for an interpretation via either short-distance new physics or consistent models of long-distance new physics, weakly coupled to the Standard Model. The electroweak scale is chosen to set the dividing line between these scenarios. In particular, we find that inverse see-saw models of neutrino mass allow for light new physics interpretations of most precision leptonic observables, such as lepton universality, lepton flavor violation, but not for the electron EDM.