  Selection rules arising from accidental or broken symmetries may be
sufficiently obscure that their agency is hidden, leading to the appearance of
"magic zeroes" -- quantities that are suppressed without apparent recourse to a
symmetry explanation. Magic zeroes and their corresponding hidden symmetries
may shed new light on parametric hierarchies in the Standard Model and beyond.
We identify the hidden symmetry responsible for a recently-discovered magic
zero, the vanishing of the putative leading contribution to the anomalous
dipole moments of the muon upon integrating out weak doublet and singlet
vector-like fermions. Some of the tools involved -- spurion analysis leveraging
discrete symmetries of the free theory, field redefinitions, spectator fields,
and non-supersymmetric non-renormalization theorems -- may prove useful in the
hunt for new magic zeroes and their hidden symmetries.
