Unified fermion mass ratios from orbifold conformal field theory

Motivated by simple-current orbifolds, where twisted sectors come with characteristic chiral and left–right “degrees,” we construct the minimal modular-covariant, permutation-symmetric, degree-zero functional of charged-fermion masses, [Formula: see text] This CFT-motivated ansatz reproduces[Formula: see text] for charged leptons (the known Koide relation) and yields a quark-sector ratio numerically consistent with [Formula: see text] when evaluated on current [Formula: see text] quark masses. The ratio is approximately invariant at one loop; full two-loop running causes only few-[Formula: see text]-level variations in [Formula: see text] over the range [Formula: see text]–[Formula: see text]. Under SM running, this predicts [Formula: see text] a precision target within reach of forthcoming lattice step-scaling calculations. The construction is numerically verified, RG-stable, and falsifiable through improved mass determinations. This framework offers a CFT-motivated route to linking low-energy flavor phenomenology and high-scale orbifold dynamics.