Search

The conservation of lepton flavor and total lepton number are no longer guaranteed in the Standard Model after the discovery of neutrino oscillations. The μ- + N (A, Z) → e+ + N(A, Z-2) conversion in a muonic atom is one of the most promising channels to investigate the lepton number violation processes, and measurement of the μ-- e + conversion is planned in future μ--e- conversion experiments with a muonic atom in a muon-stopping target. This article discusses experimental strategies to maximize the sensitivity of the μ--e+ conversion experiment by introducing the new requirement of the mass relation of M(A, Z-2) < M (A, Z-1), where M (A, Z) is the mass of the muon-stopping target nucleus, to eliminate the backgrounds from radiative muon capture. The sensitivity of the μ--e+ conversion is expected to be improved by 4 orders of magnitude in forthcoming experiments using a proper target nucleus that satisfies the mass relation. The most promising isotopes found are 40Ca and 32S. [ABSTRACT FROM AUTHOR]