Higgs-Boson Couplings Beyond the Standard Model

TL;DR

This paper investigates how potential new physics beyond the Standard Model could influence Higgs boson decays using effective field theory, identifying which operators could have observable effects within current experimental constraints.

Contribution

It identifies specific dimension-six operators that can affect Higgs decays and assesses their potential impact within existing experimental bounds.

Findings

Only a small set of operators can significantly modify Higgs decays.

Certain Higgs decay ratios remain at Standard Model levels within 1% accuracy.

Implications for Higgs branching ratios are quantified in terms of operator coefficients.

Abstract

The implications for Higgs decays of potential new physics beyond the Standard Model (BSM) are considered in the context of effective field theory, assuming perturbative decoupling. Using existing data to restrict which dimension-six operators can arise, it is shown that, given the existing experimental constraints, only a small number of operators can affect the decays of the Higgs: those that may be potentially-tree-generated (PTG) and modify the Higgs-fermion couplings, or those that may be loop-generated (LG) that modify the Higgs couplings to photon-photon, Z-photon and gluon-gluon. Implications for specific branching ratios are given in terms of the coefficients of various dimension six operators. In such a scenario, the ratios Width(H -> WW*)/Width(H -> ZZ*) and Width(H -> W l nu)/Width(H -> Z l l) equal to their standard model values to an accuracy of O(1%) or less.