Probing heavy neutrinos in the COMET experiment

Abstract

We argue that the COMET experiment-a dedicated experiment for the μ-e conversion search- has a good potential to search for heavy neutrinos in the mass range 1MeV ≫ M. ≫ 100MeV. The stopped muons captured by the target nuclei or decaying in orbit efficiently produce heavy neutrinos via the active-sterile mixing. The produced heavy neutrinos then decay to electron- positron pairs (plus an active neutrino), which charged particles hit the cylindrical drift chamber surrounding the target. If the backgrounds from gamma rays are sufficiently rejected by some method, the expected sensitivity becomes comparable to the PS191 bound when the COMET experiment achieves ∼1017 stopping muons in the target.