Accidental Suppression of Wilson Coefficients in Higgs Coupling

TL;DR

This paper investigates an accidental suppression phenomenon in Higgs effective couplings, where certain dimension-6 operators are unexpectedly smaller, impacting BSM physics searches at colliders.

Contribution

It identifies and discusses the accidental suppression of specific Higgs couplings in portal models, highlighting the lack of symmetry-based explanations and suggesting avenues for further research.

Findings

Suppression of $|H|^6$ coupling compared to $ig( abla |H|^2ig)^2$

Persistence of suppression across various portal models

Constraints on Wilson coefficients at HL-LHC and future colliders

Abstract

Higgs couplings are essential probes for physics beyond the Standard Model (BSM) since they can be modified by new physics, such as through the Higgs portal interaction $|H|^2\mathcal{O}$. These modifications influence Higgs interactions via dimension-6 operators of the form $ \left(\partial |H|^2\right)^2$ and $|H|^6$, which are generally expected to be of comparable size. This paper discusses a phenomenon of accidental suppression, where the $|H|^6$ coupling is significantly smaller than $\left(\partial |H|^2\right)^2$. This suppression, arising from the truncation of the tree-level effective potential, lacks a clear symmetry explanation but persists in portal models. This paper aims to inspire further studies on additional instances of accidental suppression without symmetry explanations or a general framework to characterize such suppression. We also discuss constraints, at the HL-LHC and future colliders, on the Wilson coefficients of the two dimension-6 operators for various benchmark scenarios of the concrete model.