Higgs Mass Bounds from Renormalization Flow for a Higgs-top-bottom model

TL;DR

This paper re-examines the lower bounds on the Higgs mass within a chiral Yukawa model using exact fermion determinant results and the functional renormalization group, challenging traditional stability-based bounds.

Contribution

It introduces a new perspective on Higgs mass bounds by analyzing the model with exact fermion determinants and flexible bare potentials, relaxing previous stability constraints.

Findings

No indication of vacuum instability from top-fluctuations with finite cutoff.

Lower Higgs mass bounds depend on the form of the bare potential.

More general bare potentials can relax the stability-based bounds.

Abstract

We study a chiral Yukawa model mimicking the Higgs-top-bottom sector of the standard model. We re-analyze the conventional arguments that relate a lower bound for the Higgs mass with vacuum stability in the light of exact results for the regularized fermion determinant as well as in the framework of the functional renormalization group. In both cases, we find no indication for vacuum instability nor meta-stability induced by top-fluctuations if the cutoff is kept finite but arbitrary. A lower bound for the Higgs mass arises for the class of standard bare potentials of \phi^4 type from the requirement of a well-defined functional integral (i.e., stability of the bare potential). This consistency bound can however be relaxed considerably by more general forms of the bare potential without necessarily introducing new meta-stable minima.