The Two Scales of New Physics in Loop-Induced Higgs Couplings

TL;DR

This paper explores how anomalies in Higgs couplings can reveal two separate new physics scales, providing a method to infer properties of potential new particles from collider measurements.

Contribution

It introduces a novel approach linking Higgs coupling anomalies to bounds on both fermionic and bosonic new physics scales, extending previous analyses to loop-induced couplings.

Findings

Upper bounds on new bosonic scales derived from fermionic anomalies

Comparison of sensitivity projections for HL-LHC and future colliders

Extension of previous Higgs coupling analyses to loop-induced processes

Abstract

Probing new physics through precise measurements of Higgs boson couplings is a central objective of the particle collider program at the high-energy frontier. An anomaly in Higgs couplings induced solely by new fermions allows one to compute an upper bound on the mass scale of new bosons. This new bosonic scale is necessary to prevent Landau poles or vacuum instability. Consequently, a single anomalous measurement can provide insight into two distinct new physics scales. In this article, we apply this approach to the loop-induced couplings of the Higgs boson to digluons ($gg$), diphotons ($\gamma \gamma$), and $Z \gamma$, and we compare our results to the projected sensitivities of the HL-LHC and future lepton colliders. This work naturally extends our previous analysis of Higgs couplings to weak dibosons ($WW$ and $ZZ$).