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 \( {\left|H\right|}^2\mathcal{O} \) . These modifications influence Higgs interactions via dimension-6 operators of the form (∂|H|2)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 (∂|H|2)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.
