“…The sign factor (−1) N ab can be readily associated to the one we have obtained on the lattice, but the writhe did not arise in the lattice formulation. In the literature the writhe contribution is sometimes referred to as the Polyakov spin factor [32,35,[41][42][43][44]. Equation (20) relates to the representation of the partition function of a Dirac fermion in 2+1 Euclidean dimensions in terms of loops [35,[42][43][44], with the difference that in our case the parity anomaly factor implies that the fermions are massless [30,[45][46][47].…”