CERN's CMS Experiment Directly Observes Leptons Emitting from Protons After Decades of Search

After more than 50 years of research, the CMS experiment at CERN has directly observed evidence of protons emitting leptons (electrons, muons, and taus), as predicted by the Standard Model of particle physics. This observation, based on data collected between 2016 and 2026, provides the first strong evidence of muon-muon scattering and offers new avenues for exploring physics beyond the Standard Model.