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. |