Naturalness and the muon magnetic moment

A bstract We study a predictive model for explaining the apparent deviation of muon anomalous magnetic moment from Standard Model expectation. There are no new scalars and hence hierarchy puzzles beyond those associated with Higgs; only particles at TeV scale vector-like singlet doublet leptons. Interestingly, this simple provides calculable example violating Wilsonian notion naturalness: despite absence any symmetries prohibiting its generation, coefficient naively leading dimension-six operator ( g − 2) vanishes one-loop. While effective field theorists interpret either as surprising UV cancellation power divergences, or delicate between matching IR corrections to parametrically separated scales, there is explanation in full theory: loop integrand total derivative function vanishing both deep IR. The contribution arises dimension-eight operators, thus required masses fermions lower than expected, sizeable portion parameter space already covered by direct searches LHC. viable free fine-tuning mass will be fully future LHC searches, all can probed precision measurements planned lepton colliders.