Anomalous Higgs Couplings at the LHC

TL;DR

This paper explores how new physics beyond the Standard Model could modify Higgs couplings at the LHC, using an effective Lagrangian approach to identify potential signals and their origins.

Contribution

It provides a model-independent analysis of Higgs and Higgs-gauge operators and their possible origins from heavy messenger exchanges, aiding in the interpretation of LHC data.

Findings

Early signals may indicate simultaneous modifications of Higgs-fermion and Higgs-gauge couplings.

Discrimination between different new physics scenarios becomes possible with more LHC data.

Discovering a new scalar doublet may require future collider technology due to the need to measure Higgs self-couplings.

Abstract

We discuss the impact and potential discovery of physics beyond the Standard Model, coupling to the Higgs sector, at the LHC. Using a model-independent effective Lagrangian approach, pure Higgs and Higgs-gauge operators are analyzed, and their origin in terms of tree-level exchange of unknown heavy messengers is systematically derived. It is demonstrated that early signals at the LHC may result from a simultaneous modification of Higgs-fermion and Higgs-gauge boson couplings induced by those operators, pointing towards singlet scalar or a triplet vector -- barring fine-tuned options. Of course, the Higgs discovery itself will also be affected by such new couplings. With increasing statistics, the remaining options can be discriminated from each other. On the other hand, the discovery of a new scalar doublet may require technology beyond the LHC, since the Higgs self-couplings have to be measured. Our conclusions are based on the complete set of tree-level decompositions of the effective operators unbiased by a specific model.