Invisible Z decay width bounds on active-sterile neutrino mixing in the (3+1) and (3+2) models

TL;DR

This paper uses measurements of the invisible Z decay width to set bounds on active-sterile neutrino mixing in (3+1) and (3+2) models, providing constraints on sterile neutrino properties.

Contribution

It introduces a method to constrain sterile neutrino mixing parameters using Z decay data in extended neutrino models.

Findings

Bounds on active-sterile mixing matrix elements derived

Constraints applicable to light sterile neutrinos in eV range

Limits improve understanding of sterile neutrino parameter space

Abstract

In this work we consider the standard model extended with singlet sterile neutrinos with mass in the eV range and mixed with the active neutrinos. The active-sterile neutrino mixing renders new contributions to the invisible Z decay width which, in the case of light sterile neutrinos, depends on the active-sterile mixing matrix elements only. We then use the current experimental value of the invisible Z decay width to obtain bounds on these mixing matrix elements for both (3+1) and (3+2) models.