Portals into Higgs vacuum stability

TL;DR

This paper explores how extending the Standard Model with vector-like fermions can stabilize the Higgs vacuum up to the Planck scale, revealing new mechanisms and potential collider signatures.

Contribution

It demonstrates that gauge portals via new charge carriers can significantly enhance Higgs stability and identifies models with TeV-range VLFs accessible at the LHC.

Findings

Gauge portal mechanism promotes stability with minimal modifications.

Models with TeV-range vector-like fermions are viable and testable at LHC.

Flavor constraints push fermion masses to very high scales.

Abstract

We address the notorious metastability of the standard model (SM) and promote it to a model building task: What are the new ingredients required to stabilize the SM up to the Planck scale without encountering subplanckian Landau poles? Using the SM extended by vector-like fermions (VLFs), we chart out the corresponding landscape of Higgs stability. We find that the gauge portal mechanism, triggered by new SM charge carriers, opens up sizeable room for stability in a minimally invasive manner. We also find models with Higgs criticality, and Yukawa portals opening up at stronger coupling. Several models allow for VLFs in the TeV-range, which can be searched for at the LHC. For nontrivial flavor structure severe flavor-changing neutral current constraints arise which complement those from stability, and push lower fermion masses up to $\mathcal{O}(10^3\,\text{TeV})$.