A bstract The μ - e conversion process is one of the most powerful ways to test lepton-flavor-violating (LFV) interactions involving charged leptons. The standard model with massive neutrinos predicts an extremely low rate for μ - e conversion, making this process an excellent probe for testing LFV arising from new physics. Among many theoretical models that can induce LFV, the Supersymmetric model with R-parity violating interactions is one of the most studied for μ - e conversion. In this work, we revisit trilinear R -parity violating interactions for μ - e conversion, considering renormalization group (RG) running effects from high to low energy scales. The μ - e conversion, μ → eγ , and μ → eee experimental data are compared to give upper limits on the relevant 15 combinations of the trilinear λ′ couplings and 6 combinations of the λ couplings, certain of which are underexplored in previous studies. We find that RG running effects influence the limits by no more than 30% in most cases, but can improve constraints by ~80% in certain combinations, which cannot be neglected. In the near future, COMET and Mu2e are expected to begin data-taking and aim to provide the most stringent constraints on μ - e conversion. These next-generation μ - e experiments have the ability to give much more comprehensive examinations on most trilinear coupling combinations than the μ → eγ and μ → 3 e decay experiments. The μ - e experiments will not only deepen our understanding of LFV but also provide a crucial way to examine the underlying new physics contributions.
Xiao et al. (2026) studied this question.