Rationale for UV-filtered clover fermions

We study the contributions Sigma_0 and Sigma_1, proportional to a^0 and a^1,to the fermion self-energy in Wilson's formulation of lattice QCD withUV-filtering in the fermion action. We derive results for m_{crit} and therenormalization factors Z_S, Z_P, Z_V, Z_A to 1-loop order in perturbationtheory for several filtering recipes (APE, HYP, EXP, HEX), both with andwithout a clover term. The perturbative series is much better behaved withfiltering, in particular tadpole resummation proves irrelevant. Ournon-perturbative data for m_{crit} and Z_A/(Z_m*Z_P) show that the combinationof filtering and clover improvement efficiently reduces the amount of chiralsymmetry breaking -- we find residual masses am_{res}=O(10^{-2}).Comment: 25 pages, 4 figures; v2: typo in eqn. (37) fixed [agrees with published version