Fixed-point actions in 1-loop perturbation theory Original Research Article

It has been pointed out in recent papers that the example considered earlier in the O(N) δ-model to test whether fixed-point actions are 1-loop perfect actually checked classical perfection only. To clarify the issue we constructed the renormalized trajectory explicitly in 1-loop perturbation theory. We found that the fixed-point action is not exactly 1-loop perfect. The cut-off effects are, however, strongly reduced also on the 1-loop level relative to those of the standard and tree level improved Symanzik actions. Some points on off- and on-shell improvement, Symanzikʹs program and fixed-point actions are also discussed.