Role of dimension-eight operators in an EFT for the 2HDM

TL;DR

This paper investigates the impact of including dimension-eight operators in the SMEFT framework when matching to the 2HDM, analyzing how these higher-order terms affect Higgs coupling deviations and related experimental constraints.

Contribution

It provides a detailed analysis of the role of dimension-eight operators in SMEFT when matched to the 2HDM, highlighting their significance beyond the commonly used dimension-6 truncation.

Findings

Dimension-eight operators can significantly influence Higgs coupling predictions.

Matching SMEFT to 2HDM requires careful consideration of higher-order terms.

Numerical analysis shows the importance of assumptions about the high-scale expansion.

Abstract

The Standard Model effective field theory (SMEFT) is the tool of choice for studying deviations of Higgs couplings from the Standard Model predictions. The SMEFT is an expansion in an infinite tower of higher dimension operators, which is typically truncated at dimension-6. We consider the effective theory including dimension-8 operators and examine the matching to the 2 Higgs Doublet Model (2HDM) that is assumed to be valid at some high scale. Both the limits from the direct production of single Higgs bosons and the indirect limits on the Higgs tri-linear coupling are considered in the context of the SMEFT matched to the 2HDM, and the importance of the assumptions about the expansions in powers of the high scale are examined numerically.