Systematically testing singlet models for (g − 2) μ
Rodolfo Capdevilla (Department of physics, University of Toronto, Saint George Street, Toronto, Ontario, Canada, Perimeter Institute for Theoretical Physics, Caroline Street North, Waterloo, Ontario, Canada); David Curtin (Department of physics, University of Toronto, Saint George Street, Toronto, Ontario, Canada); Yonatan Kahn (Department of Physics, University of Illinois at Urbana-Champaign, West Green Street, Urbana, IL, USA, Illinois Center for Advanced Studies of the Universe, University of Illinois at Urbana-Champaign, West Green Street, Urbana, IL, USA); Gordan Krnjaic (Fermi National Accelerator Laboratory, Kirk Street, Batavia, IL, USA, Department of Astronomy and Astrophysics, University of Chicago, South Ellis Avenue, Chicago, IL, USA, Kavli Institute for Cosmological Physics, University of Chicago, South Ellis Avenue, Chicago, IL, USA)
We comprehensively study all viable new-physics scenarios that resolve the muon (g − 2) μ anomaly with only Standard Model singlet particles coupled to muons via renormalizable interactions. Since such models are only viable in the MeV–TeV mass range and require sizable muon couplings, they predict abundant accelerator production through the same interaction that resolves the anomaly. We find that a combination of fixed-target (NA64μ, M 3), B-factory (BABAR, Belle II), and collider (LHC, muon collider) searches can cover nearly all viable singlets scenarios, independently of their decay modes. In particular, future muon collider searches offer the only certain test of singlets above the GeV scale, covering all higher masses up to the TeV-scale unitarity limit for these models. Intriguingly, we find that $$ \mathcal{O}\left(100\ \mathrm{GeV}\right) $$ muon colliders may yield better coverage for GeV-scale singlets compared to TeV-scale concepts, which has important implications for the starting center-of-mass energy of a staged muon collider program.
