A six-gluon obstruction to dimension-independent local color-kinematics duality at one loop

Abstract

We establish an obstruction to dimension-independent local color-kinematics duality for the one-loop six-gluon amplitude in pure Yang-Mills theory. The maximal and fivefold cuts admit a polynomial solution, but no allowed contact correction reproduces a required fourfold cut. We consider parity-even Lorentz-polynomial numerators, multilinear in arbitrary transverse external polarizations, with conventional quadratic propagators, global graph identities, and pointwise formal-color cut equality. No dimension-specific Gram identities are imposed. In the sector containing one polarization inner product, the higher cuts determine the complete remaining contact freedom. Every such correction obeys an exact coefficient relation that the required physical residual violates, independently of the chosen higher-cut solution. The violation is proportional to the transverse internal vector-state count and is nonzero at every nonzero value of its algebraic continuation. Momentum homogeneity extends the degree-six contradiction to all finite polynomial degrees. An all-multiplicity polynomial family retaining these representation conditions is therefore excluded.