Full top quark mass dependence in Higgs boson pair production at NLO

TL;DR

The authors deliver the first fully differential NLO calculation of Higgs boson pair production via gluon fusion that retains the exact top-quark mass dependence. By comparing to HEFT-based approximations and performing a 1/mt^2 expansion, they show substantial differences, with mass effects reaching up to 50% in differential tails and a global cross-section reduction of about 14% at 14 TeV and 24% at 100 TeV relative to Born-improved HEFT. The study also probes how the Higgs self-coupling λ_hhh shapes both total rates and kinematic distributions, highlighting strong interference effects and potential discriminants for non-SM scenarios. These results underscore the necessity of using full mt-dependent NLO predictions for precise Higgs physics and set the stage for combining with NNLO HEFT results to improve accuracy.

Abstract

We study the effects of the exact top-quark mass dependent two-loop corrections to Higgs boson pair production by gluon fusion at the LHC and at a 100 TeV hadron collider. We perform a detailed comparison of the full next-to-leading order result to various approximations at the level of differential distributions and also analyse non-standard Higgs self-coupling scenarios. We find that the different next-to-leading order approximations differ from the full result by up to 50 percent in relevant differential distributions. This clearly stresses the importance of the full NLO result.

Figures (14)

• Figure 1: Diagrams contributing to the process $gg\to hh$ at leading order.
• Figure 2: Examples of two-loop diagrams entering the virtual amplitude.
• Figure 3: Examples of diagrams contributing to the real radiation part at NLO. The diagrams in the second row do not lead to infrared singularities.
• Figure 4: Comparison of the virtual part as defined in Eq. (\ref{['eq:V+I']}) with full top-quark mass dependence to various orders in a $1/m_t^{2}$ expansion. $V^\prime_N$ denotes the Born-improved HEFT result to order $N$ in the $1/m_t^{2}$ expansion, i.e. $V^\prime_N=V_N\,B_{FT}/B_N$. The results for the orders $N=4,5,6$ have been provided to us by Jens Hoff Grigo:2015dia.
• Figure 5: Higgs boson pair invariant mass distribution $m_{hh}$ at $\sqrt{s}=14$ TeV and $\sqrt{s}=100$ TeV for absolute values (left panels) and normalised to the corresponding total cross section (right panels).