Imposing limits on heavy neutral leptons from the suppression of neutrino CC events at the DUNE Near Detector

We assess how the production of heavy neutral leptons (HNL) at the DUNE flux can affect the number of neutrino charged current (CC) events at the DUNE ND LArTPC. A deficit in the number of CC events at the LArTPC should be observed for HNLs with masses below the kaon mass. We estimate upper limits on the mixing parameters from the aforementioned deficit. We find that these limits are stronger than those that can be achieved by DUNE direct searches for masses below 10 MeV and are at least 1 order of magnitude better than current constraints for masses below 1 MeV.