Vacuum Stability and Electroweak Precision in the Two Higgs Doublet Model with Vector-Like Quarks

TL;DR

This paper analyzes the vacuum stability and electroweak precision constraints of the Two-Higgs Doublet Model extended with vector-like quarks, identifying viable parameter regions across different fermion representations and model types.

Contribution

It provides a comprehensive RG analysis and electroweak fit for the 2HDM with vector-like quarks, including detailed expressions and representation effects.

Findings

Certain parameter regions satisfy vacuum stability and electroweak constraints.

Vector-like quark representations significantly influence the allowed parameter space.

Differences between Type-I and Type-II models are highlighted in the analysis.

Abstract

We present a comprehensive analysis of the vacuum stability of the Two-Higgs Doublet Model, for both Type-I and Type-II, augmented by vector-like quarks in either singlet, doublet or triplet representations. We review the model briefly before introducing the extra fermionic states and their interactions, and impose restrictions on the parameters coming both from theoretical considerations and experimental bounds. We then study the renormalization group equation evolution of the parameters of the model in order to isolate the parameter regions that satisfy vacuum stability requirements. We then add the electroweak precision observables to insure that the resulting parameter space is consistent with the data. We include complete expressions for the renormalization group equations and the S and T parameters used. Finally we summarize the effects of various vector-like quark representations on the parameter space. We indicate the regions constrained, highlighting the differences between representations in Type-I and Type-II, and pinpoint the effects of the interplay between the extended model and the additional fermions.