Searches for heavy neutral leptons at the LHC

Heavy neutral leptons (HNLs) are introduced in extensions of the standard model (SM) of particle physics to explain the nonzero neutrino masses via the seesaw mechanism. They can also be a dark matter candidate, or provide a mechanism for the generation of the matter-antimatter asymmetry in the universe. At the CERN Large Hadron Collider (LHC), HNLs could be produced in proton-proton collisions through various processes. The ATLAS and CMS experiments have performed HNL searches covering a wide mass range from a few GeV to several TeV. Here, a selection of recent results is presented that are based on the full pp collisions data set at 13 TeV recorded during Run 2 of the LHC (2015-2018).