Extending sensitivity for low-mass neutral heavy lepton searches

We point out the importance of two-body final states of weak isosinglet neutral heavy leptons predicted in several models of new physics beyond the standard model. We concentrate on muon-type neutral heavy leptons L_μ⁰ with a mass $M<2$ GeV that can be searched for with increased sensitivity at a new round of neutrino experiments at CERN and Fermilab. Providing explicit decay rate formulas for the eeν, eμν, μμν, πμ, ρμ, and a₁μ final states, we use general scaling features to estimate the sensitivity of L_μ⁰ searches in current and future experiments, emphasizing the importance of the πμ decay mode.