Higgs boson pair production at NNLO with top quark mass effects (1803.02463v1)

Abstract: We consider QCD radiative corrections to Higgs boson pair production through gluon fusion in proton collisions. We combine the exact next-to-leading order (NLO) contribution, which features two-loop virtual amplitudes with the full dependence on the top quark mass $M_t$, with the next-to-next-to-leading order (NNLO) corrections computed in the large-$M_t$ approximation. The latter are improved with different reweighting techniques in order to account for finite-$M_t$ effects beyond NLO. Our reference NNLO result is obtained by combining one-loop double-real corrections with full $M_t$ dependence with suitably reweighted real--virtual and double-virtual contributions evaluated in the large-$M_t$ approximation. We present predictions for inclusive cross sections in $pp$ collisions at $\sqrt{s}$=13, 14, 27 and 100TeV and we discuss their uncertainties due to missing $M_t$ effects. Our approximated NNLO corrections increase the NLO result by an amount ranging from +12% at $\sqrt{s}$=13TeV to +7% at $\sqrt{s}$=100TeV, and the residual uncertainty from missing $M_t$ effects is estimated to be at the few percent level. Our calculation is fully differential in the Higgs boson pair and the associated jet activity: we also present predictions for various differential distributions at $\sqrt{s}$=14 and 100TeV. Our results represent the most advanced perturbative prediction available to date for this process.

• The paper presents a hybrid NNLO calculation that integrates exact NLO top mass effects with the large-Mt approximation.
• QCD corrections yield a significant cross-section increase, exemplified by a +12% boost at 13 TeV collisions.
• Reweighting techniques effectively bridge HEFT simplifications and full mass dependence, enhancing predictions for LHC analyses.

Overview of Higgs Boson Pair Production at NNLO Including Top Quark Mass Effects

The paper delivers a comprehensive analysis of the quantum chromodynamics (QCD) radiative corrections to the production of Higgs boson pairs through gluon fusion in proton-proton (pp) collisions. This paper is grounded in combining the precision of next-to-next-to-leading order (NNLO) calculations in the large top quark mass ($M_t$) approximation with enhancements from exact mass effects at next-to-leading order (NLO). The theoretical approach aims to bridge the gap between the simplified assumptions of the Higgs Effective Field Theory (HEFT) and full top quark mass dependence calculations.

Methodological Approach

To achieve the stated objective, the authors utilize a blend of computational strategies:

1. NLO and NNLO Calculations: Incorporating exact NLO contributions with full $M_t$ dependence, alongside NNLO corrections evaluated in the large-$M_t$ limit.
2. Reweighting Techniques: Various reweighting methodologies are employed to introduce finite-$M_t$ effects that are not captured at NLO into the NNLO framework.
3. Differential Predictions: The paper presents predictions for inclusive cross sections at several center-of-mass energies ($\sqrt{s} = 13, 14, 27,$ and $100$ TeV). Furthermore, it explores differential distributions at $\sqrt{s} = 14$ and $100$ TeV.

Major Findings

The NNLO corrections contribute a notable augmentation of the cross sections as follows:

• An increase of approximately $+12\%$ at $\sqrt{s}=13$ TeV.
• A relatively lower increase of $+7\%$ at $\sqrt{s}=100$ TeV.

The residual uncertainties from missing $M_t$ effects are estimated to be minor, at the level of a few percent. The paper confirms that these corrections and uncertainties are the most precise to date for Higgs boson pair production through this gluon fusion channel.

Implications

The implications of this research are manifold:

• Theoretical Impact: The findings reinforce our theoretical understanding of higher-order corrections in Higgs physics, offering more accurate perturbative predictions.
• Practical Insights: With the Large Hadron Collider (LHC) emphasizing Higgs boson studies, these improved predictions are critical for upcoming experimental runs, particularly in discerning the Higgs self-coupling from Higgs boson pair production.

Future Directions

Future research should continue to refine these theoretical approaches by exploring:

1. Enhanced Reweighting Methodologies: Developing more sophisticated techniques that can further diminish uncertainties due to missing mass effects.
2. Broadening the Energy Scope: Extending precision studies to cover more LHC scenarios, including potential future colliders beyond 100 TeV.
3. Incorporating Electroweak Corrections: Addressing contributions outside QCD alone, particularly focusing on electroweak corrections that might become significant at higher energies.

The paper represents a substantial progression in QCD calculations for Higgs boson pair production, achieving enhanced accuracy and posing new questions for subsequent theoretical and experimental investigations in particle physics.