The Technical FineTuning Problem in Renormalized Perturbation Theory.
Abstract
We study the technicalas opposed to physical finetuning problem, i.e. the stability of treelevel gauge hierarchies at higher orders in renormalized perturbation theory, in a number of different models. These include softlybroken supersymmetric models, and nonsupersymmetric ones with a hierarchy of spontaneouslybroken gauge symmetries. The models are renormalized using the BPHZ prescription, with momentum subtractions. Explicit calculations indicate that the treelevel hierarchy is not upset by the radiative corrections, and consequently no further finetuning is required to maintain it. Furthermore, this result is shown to run counter to that obtained via Dimensional Renormalization, (the only scheme used in previous literature on the subject). The discrepancy originates in the inherent local ambiguity in the finite parts of subtracted Feynman integrals. We conclude thatwithin fullyrenormalized perturbation theorythe answer to the technical finetuning question (in the sense of whether the radiative corrections will "readily" respect the tree level gauge hierarchy or not) is contingent on the renormalization scheme we use to define the model at the quantum level, rather than on the model itself. In other words, the need for finetuning, when it arises, is an artifact of the application of a certain class of renormalization schemes. We emphasize that the issue is purely technical in nature, and that this result does not imply that physical properties are renormalization scheme dependent.
 Publication:

Ph.D. Thesis
 Pub Date:
 1983
 Bibcode:
 1983PhDT........34F
 Keywords:

 Physics: Elementary Particles and High Energy