On the impact of dimension-eight SMEFT operators on Higgs measurements

Understand

Using the production of a Higgs boson in association with a $W$ boson as a test case, we assess the impact of dimension-8 operators within the context of the Standard Model Effective Field Theory.

• Dimension-8--SM-interference and dimension-6-squared terms appear at the same order in an expansion in $1/\Lambda$, hence dimension-8 effects can be treated as a systematic uncertainty on the new physics inferred from analyses using dimension-6 operators alone.
• To study the phenomenological consequences of dimension-8 operators, one must first determine the complete set of operators that can contribute to a given process.
• We accomplish this through a combination of Hilbert series methods, which yield the number of invariants and their field content, and a step-by-step recipe to convert the Hilbert series output into a phenomenologically useful format.