Abstract
Measurements of multi-boson processes provide a probe of the EW sector of
the SM. The vast integrated luminosity of 139 /fb recorded by the ATLAS
experiment during Run 2 of the LHC allows for very precise measurements
which can be used as benchmarks to test state-of-the-art theoretical
predictions. It also allows for the observation and study of much rarer
processes which were unaccessible at previous colliders. The fiducial
cross-section measurements for Zy and Zyy production are presented and their
impact on testing predictions and constraining new physics effects are
discussed.