Mass Effects in the Higgs-Gluon Coupling: Boosted vs Off-Shell Production

TL;DR

Problem: Understand how top-quark loops shape the Higgs–gluon coupling across momentum scales. Method: Develop a state-of-the-art NLO multi-jet merging framework with full top-mass dependence, and compare boosted Higgs production with off-shell Higgs production within a unified κ_t/κ_g (or Δ_t/Δ_g) Lagrangian. Findings: Top-mass effects are substantial in boosted and off-shell regimes, factorize by jet multiplicity, and can constrain the loop structure and possible dimension-6 contributions; width measurements require knowledge of the loop momentum dependence and are not model-independent. Significance: The work provides a practical, data-driven way to test the loop-induced Higgs–gluon coupling in LHC Run 2/3 and informs strategies for width extraction and new-physics searches.

Abstract

In the upcoming LHC run we will be able to probe the structure ofthe loop--induced Higgs--gluon coupling through kinematics. First, we establish state-of-the-art simulations with up to two jets to next-to-leading order including top mass effects. They allow us to search for deviations from the low-energy limits in boosted Higgs production. In addition, the size of the top mass effects suggests that they should generally be included in Higgs studies at the LHC. Next, we show how off-shell Higgs production with a decay to four leptons is sensitive to the same top mass effects. We compare the potential of both methods based on the same top--Higgs Lagrangian. Finally, we comment on related model assumptions required for a Higgs width measurement.

Figures (11)

• Figure 1: Sample Feynman diagrams contributing for Higgs production with up to 2 jets at leading order.
• Figure 2: Transverse momentum distribution $p_{T,H}$ for $H\rightarrow WW$+jets production at LO with Sherpa (left panel) and Pythia8 (right panel). We present the distributions for exclusive and merged jet samples with finite top mass effects $(m_t=173~{\rm GeV})$ and in the low-energy approximation $(m_t\rightarrow \infty)$. We assume the LHC at $\sqrt{S}=13$ TeV.
• Figure 3: Sample one-loop Feynman diagrams contributing to the Higgs and Higgs-jet production. On the top we display the NLO real corrections and on the bottom the virtual contributions.
• Figure 4: Transverse momentum distribution $p_{T,H}$ for $H\rightarrow WW$+jets production with Sherpa at NLO (left panel). We present the distributions for exclusive and merged jet samples with finite top mass effects $(m_t= 173~{\rm GeV})$ and in the low-energy approximation $(m_t\rightarrow \infty)$. In the right panel we show the $p_{T,H}$-dependent $K$-factor for $H$ and $H+1$ jet production.
• Figure 5: Normalized $p_{T,ll}$ (left) and $\Delta\phi_{jj}$ (right) distributions for the $H\rightarrow WW$ signal and the dominant backgrounds. All universal cuts listed in Tab \ref{['tab:cuts1']} are already applied. We assume the LHC at $\sqrt{S}=13$ TeV.