A new concept proposes producing collisions between positive muons (μ⁺) and electrons at CERN's future FCC-ee collider, or its Chinese counterpart CEPC, at centre-of-mass energies between 1 and 2 TeV and an average luminosity above 10³⁴ cm⁻² s⁻¹. The novelty is that these μ⁺e⁻ collisions would run concurrently with the e⁺e⁻ collisions for which the machine is designed, without sacrificing the FCC-ee's own physics programme.

The scientific motivation cited includes the prospect of measuring Higgs boson self-interaction, a key observable for reconstructing the shape of the Higgs field potential and testing whether the electroweak symmetry breaking mechanism follows the Standard Model prediction. Muon beams offer an advantage over electron beams: the muon, being some 200 times heavier, radiates far less in curves, allowing multi-TeV energies in compact rings where a linear e⁺e⁻ collider would be the conventional alternative.

The paper describes the design of the FCC-μe complex: a source of ultra-cold antimuons, an injection accelerator (muon booster) and the main muon ring, together with basic considerations on the machine-detector interface and expected performance. The same scheme would yield an associated neutrino factory, exploiting the decay of the stored muons.

The work concludes by stressing the relevance of such antimuon beams not only for FCC-ee but for any future high-energy storage ring and for neutrino science.