Strong non-ultralocality of Ginsparg–Wilson fermionic actions Original Research Article

It is shown that it is impossible to construct a free theory of fermions on infinite hypercubic Euclidean lattice in even number of dimensions that: (a) is ultralocal, (b) respects the symmetries of hypercubic lattice, (c) chirally nonsymmetric part of its propagator is local, and (d) describes single species of massless Dirac fermions in the continuum limit. This establishes non-ultralocality for arbitrary doubler-free Ginsparg–Wilson fermionic action with hypercubic symmetries (“strong non-ultralocality”), and complements the earlier general result on non-ultralocality of infinitesimal Ginsparg–Wilson–Lüscher symmetry transformations (“weak non-ultralocality”).