[Paper Review] Higgs boson production in association with a photon via weak boson fusion

K. Arnold, Terrance Figy+2 more|arXiv (Cornell University)|Oct 11, 2011

Particle physics theoretical and experimental studies3 citations

TL;DR

This paper presents a next-to-leading order (NLO) QCD calculation for Higgs boson production in association with a photon via weak boson fusion (WBF) at the LHC, implemented in the VBFNLO Monte Carlo framework. The study finds small overall corrections to the cross section—within 2–4% scale uncertainties—while NLO effects significantly alter the shape of key distributions, particularly in high-transverse-momentum regions, enhancing the process's potential for probing the Hbb Yukawa coupling with reduced theoretical uncertainty and improved background suppression.

ABSTRACT

We present next-to-leading order QCD corrections to Higgs production in association with a photon via weak boson fusion at a hadron collider. Utilizing the fully flexible parton level Monte-Carlo program VBFNLO, we find small overall corrections, while the shape of some distributions is sensitive to radiative contributions in certain regions of phase-space. Residual scale uncertainties at next-to-leading order are at the few-percent level. Being perturbatively well under control and exhibiting kinematic features that allow to distinguish it from potential backgrounds, this process can serve as a valuable source of information on the $Hb\bar{b}$ Yukawa coupling.

Motivation & Objective

• To provide a precise theoretical prediction for Higgs boson production in association with a photon via weak boson fusion at the LHC.
• To reduce theoretical uncertainties in the Hbb Yukawa coupling measurement by computing NLO-QCD corrections to the signal process.
• To assess the impact of QCD radiative corrections on kinematic distributions and background suppression in the H→b¯bγ final state.
• To evaluate the robustness of the signal topology under NLO corrections, particularly in regions sensitive to new physics.
• To enable accurate simulation of the Hγjj process using the VBFNLO framework for future LHC analyses.

Proposed method

• Employed the VBFNLO parton-level Monte Carlo program to compute NLO-QCD corrections to the pp→Hγjj process.
• Used factorization and renormalization scales set to μF=ξFQi and μR=ξRQi, with ξF,ξR∈[0.5,2] to estimate scale uncertainties.
• Applied WBF cuts (Δη>2, pT>20 GeV for tagging jets) to isolate the weak boson fusion topology.
• Neglected t- and u-channel interference terms and V→qq̄ decays to speed up computation while preserving accuracy in relevant phase-space regions.
• Calculated relative corrections using δ(O) = [dσ(ξ)/dO]/[dσ^NLO(ξ=1)/dO] − 1 to quantify NLO effects on observables.
• Reconstructed the Hγ invariant mass distribution from the Higgs decay products and the photon to study signal kinematics.

Experimental results

Research questions

• RQ1 What is the size and scale dependence of NLO-QCD corrections to Higgs boson production in association with a photon via weak boson fusion?
• RQ2 How do NLO corrections affect the shape of key kinematic distributions such as the transverse momentum of the hardest tagging jet?
• RQ3 To what extent do NLO corrections reduce theoretical uncertainties in the H→b¯bγ signal compared to leading-order predictions?
• RQ4 How effective is the central photon requirement in suppressing QCD backgrounds while preserving the signal rate?
• RQ5 What is the impact of destructive interference between fermion-line and W-boson line photon emission on the signal rate and distribution shapes?

Key findings

• NLO-QCD corrections to the integrated cross section are small, with residual scale uncertainties at the few-percent level (≤4%) across all considered observables.
• The shape of the transverse momentum distribution of the hardest tagging jet is significantly altered by NLO corrections, with the peak shifting to lower pT values.
• Relative corrections to the transverse momentum distribution exceed 10% in high-pT regions, indicating non-trivial NLO effects in phase-space sensitive to new physics.
• The invariant mass distribution of the Hγ system peaks at around 165 GeV for a 120 GeV Higgs boson, with NLO corrections improving the precision of the reconstruction.
• The signal cross section is reduced by approximately a factor of two by WBF cuts, consistent with expectations from phase-space suppression.
• The process exhibits strong suppression of QCD backgrounds due to the absence of gluon-to-photon coupling and destructive interference, enhancing signal-to-background ratio by a factor of ~3000 relative to QCD-induced backgrounds.