The role of heavy fermions

TL;DR

This paper investigates the threshold at which heavy fermions influence low-energy physics, beyond simple gauge coupling renormalization, by analyzing their mass relative to the cutoff.

Contribution

It provides a quantitative analysis of the mass scale at which heavy fermions begin to affect low-energy phenomena beyond trivial renormalization.

Findings

Heavy fermions with masses near the cutoff do not alter low-energy physics except for finite renormalization.

The study determines the critical mass scale where heavy fermions impact low-energy observables.

Results help clarify the decoupling behavior of heavy fermions in quantum field theories.

Abstract

Heavy dynamical fermions with masses around the cut-off do not change the low energy physics apart from a finite renormalization of the gauge coupling. In this paper we study how light the heavy fermions have to be to cause more than this trivial renormalization.