Non--perturbative evidence for non--decoupling of heavy fermions

Abstract

We investigate, using a $1/N$ expansion, the behavior of a parameter in the scalar--fermion sector of the standard model that shows perturbative non--decoupling as the fermion becomes heavy. This low energy parameter is related to the $S$ parameter defined through the $W_3-B$ vacuum polarization tensor. We obtain the leading $1/N$ contribution to this parameter that, if expanded perturbatively, collapses to its constant one--loop result; remarkably all the higher--order terms in the series vanish. Non--perturbatively, however, we find that as the mass of the fermion approaches the built--in cutoff scale of the theory --- the triviality scale --- the parameter is highly dependent on the implementation of the cutoff; it is non--universal, and shows non--decoupling.

10pp, harvmac, figures not included, /UCLA/92/TEP/34,UAB--FT--291

References in corpus (2)

• Decoupling a Fermion Whose Mass Comes from a Yukawa Coupling: Nonperturbative Considerations
• On the Renormalization of the S Parameter

Cited by in corpus (6)

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• Resummed corrections to the ρparameter due to a finite width of the top quark
• Study of the Decoupling of Heavy Fermions in a Z_2 Scalar-Fermion Model
• Resummed corrections to the ρparameter in the complex mass scheme
• Heavy top renormalon contribution to fermion propagators