Double insertions of SMEFT operators in gluon fusion Higgs boson production

TL;DR

This paper investigates the effects of double insertions of dimension-6 SMEFT operators in gluon fusion Higgs production, providing Feynman rules and analyzing the significance of higher-order contributions for accurate modeling.

Contribution

It introduces Feynman rules up to order 1/Λ^4 for double insertions of SMEFT operators in Higgs production and assesses the impact of various approximations in this context.

Findings

Double insertions can significantly affect the virtual amplitude.

Higher-order terms are necessary for precise predictions.

Approximations may lead to notable deviations in results.

Abstract

Deviations from the Standard Model (SM) can be parameterized in terms of the SM effective field theory (SMEFT), which is typically truncated at dimension-6. Including higher dimension operators -- as well as considering simultaneous insertions of multiple dimension-6 operators -- may be necessary in some processes, in order to correctly capture the properties of the underlying UV theory. As a step towards clarifying this in the Higgs boson production in gluon fusion process, we study double insertions of dimension-6 operators in the 1-loop virtual amplitude. We present needed Feynman rules up to $\mathcal{O}(1/\Lambda^4)$ and we numerically study the impact of various approximations to the $\mathcal{O}(1/\Lambda^4)$ expansion.