Electroweak measurements at electron-positron colliders as indirect searches for heavy neutrinos

Heavy neutrinos are part of many extensions of the Standard Model, in particular seesaw models that can explain the light neutrino masses and mixing. Future electron-positron colliders would greatly increase the precision of the measurements of electroweak processes. I will discuss how this improved precision offers new opportunities to search for the effects of heavy neutrinos. In particular, I will focus on indirect search strategies based on the modifications of the production cross-sections of W or Higgs bosons at electron-positron colliders. These searches are complementary to other observables and would allow to probe the multi-TeV mass regime at future colliders.