New global bounds on heavy neutrino mixing

Abstract

We present an updated and improved global fit analysis of precision and flavor observables so as to derive constraints on deviations from unitarity in the leptonic mixing matrix. We focus on the case in which these deviations are sourced by heavy neutrinos, such that our results can also be interpreted as bounds on their mixing with the active flavors. Our analysis is motivated by new results on key observables, such as $M_W$, $|V_{ud}|$ and $\Gamma_{\text{inv}}$.