Vices and Virtues of Higgs EFTs at Large Energy

TL;DR

This paper examines the use of Higgs production data at the LHC to constrain new physics via EFT, highlighting the energy regimes where EFT remains valid and how these constraints compare to previous experiments.

Contribution

It clarifies the conditions under which high-energy Higgs searches provide meaningful EFT constraints, especially for strongly coupled composite scenarios.

Findings

High-energy Higgs searches can constrain certain EFT operators.

EFT validity depends on specific energy regimes and operator effects.

Constraints are competitive with LEP2 in some scenarios.

Abstract

We study constraints on new physics from Higgs production at the LHC in the context of an effective field theory (EFT), focusing on Higgs searches in $HV$ ($V=W,Z$) associated production which are particularly sensitive to the high-energy behavior of certain dimension-6 operators. We show that analyses of these searches are generally dominated by a kinematic region where the generic EFT expansion breaks down, and establish under which conditions they can nevertheless be meaningful. For example, constraints from these searches on the Wilson coefficients of operators whose effects grow with energy can be established in scenarios where a particular combination of fermions and the Higgs are composite and strongly coupled: then, bounds from Higgs physics at high energy are complementary to LEP1 and competitive with LEP2.