Many models of particle physics beyond the Standard Model (BSM) predict a rate for muons turning into electrons without emitting neutrinos, which is not possible under the Standard Model. Fermilab is constructing an experiment that will be highly sensitive to this process, looking for generic signals of BSM physics. Construction is scheduled to be complete in 2026, and the experiment is planned to run for three years. https://en.wikipedia.org/wiki/Mu2e
"Construction is scheduled to be complete in 2026, and the experiment is planned to run for three years."
I have no inside information on Mu2e, but construction often takes longer than expected, and more significantly, these types of analysis often take a long time after data collection is completed. For comparison: the latest g-2 measurement was published 3 years after the analyzed data was collected; the SINDRUM II experiment (similar measurement to Mu2e) seems to have a 6 year gap between data collection and final paper. I would be surprised if the final Mu2e results are published by the end of 2030.