  It has been known for some time that the standard MHV diagram formulation of
perturbative Yang-Mills theory is incomplete, as it misses rational terms in
one-loop scattering amplitudes of pure Yang-Mills. We propose that certain
Lorentz violating counterterms, when expressed in the field variables which
give rise to standard MHV vertices, produce precisely these missing terms.
These counterterms appear when Yang-Mills is treated with a regulator,
introduced by Thorn and collaborators, which arises in worldsheet formulations
of Yang-Mills theory in the lightcone gauge. As an illustration of our
proposal, we show that a simple one-loop, two-point counterterm is the
generating function for the infinite sequence of one-loop, all-plus helicity
amplitudes in pure Yang-Mills, in complete agreement with known expressions.
