Description
We present an updated and improved global fit analysis of current flavor and electroweak precision observables to derive bounds on the mixing of heavy neutrinos.
This new analysis is motivated by new and updated experimental results on key observables such as $V_{ud}$, the invisible decay width of the $Z$ boson and the $W$ boson mass. It also improves upon previous studies by considering the full correlations among the different observables and explicitly calibrating the test statistics, which may present significant deviations from a $\chi^2$ distribution.
The results are provided for three different models: the minimal scenario with only 2 neutrinos, the next to minimal one with 3 neutrinos, and the most general one with an arbitrary number of heavy neutrinos that we parametrize via a generic deviation from a unitary lepton mixing matrix.
