Exactly massless quarks on the lattice

It is suggested that the fermion determinant for a vector-like gauge theory with strictly massless quarks can be represented on the lattice as det1+V2, where V=X(X†X)−1/2 and X is the Wilson-Dirac lattice operator with a negative mass term. There is no undesired doubling and no need for any fine tuning. Several other appealing features of the formula are pointed out.