FIXED-POINT ACTIONS FOR LATTICE FERMIONS

The fixed point actions for Wilson and staggered lattice fermions are determined by iterating renormalization group transformations. In both cases a Ene of fixed points is found. Some points have very local fixed point actions. They can be used to construct perfect lattice actions for asymptotically free fermionic theories like QCD or the Gross-Neveu model. The local fixed point actions for Wilson fermions break chiral symmetry, while in the staggered case the remnant U(1)e X U(I)o symmetry is preserved. In addition, for Wilson fermions a nonlocal fixed point is found that corresponds to free chiral fermions. The vicinity of this fixed point is studied in the Gross-Neveu model using perturbation theory.