Nondecoupling of Heavy Mirror-Fermion

TL;DR

This paper investigates whether heavy mirror-fermions decouple in the strong coupling regime of a chiral U(1) model, finding nondecoupling behavior consistent with one-loop perturbation theory through nonperturbative lattice simulations.

Contribution

It provides the first nonperturbative evidence that heavy mirror-fermions do not decouple in a four-dimensional chiral gauge theory, supporting the one-loop perturbative predictions.

Findings

Heavy mirror-fermions do not decouple in the strong coupling regime.

Numerical lattice results support the one-loop perturbation theory.

Nondecoupling persists across different lattice sizes.

Abstract

According to one-loop perturbation theory, fermions whose masses are totally generated from Yukawa couplings do not decouple in the heavy mass limit. We investigate this issue nonperturbatively in the strong coupling regime of the chiral $U(1)$ mirror-fermion model in four dimensions. Our numerical results, obtained on $6^3\cdot 16$, $6^3\cdot 24$ and $8^3\cdot 16$ lattices, indicate nondecoupling of heavy fermion and mirror-fermion, thus supporting the one-loop picture.