N3LO+N3LL QCD improved Higgs pair cross sections

Abstract We report a new calculation of the soft-gluon threshold resummation for the Higgs boson pair production in the dominant production mode — gluon-gluon fusion — up to the next-to-next-to-next-to-leading logarithmic (N3LL) accuracy. After matching N3LL to the next-to-next-to-next-to-leading order (N3LO) QCD calculation in the infinite top quark mass approximation, we show that the central values of the inclusive cross sections are quite stable with respect to N3LO, while the conventional renormalisation and factorisation scale uncertainties are reduced by a factor of two, reaching to the subpercent level. Our study further consolidates the good asymptotic perturbative convergence. After combining with the full top-quark mass dependent next-to-leading order QCD results, our most advanced predictions are presented for both the inclusive total cross sections and the differential invariant mass distributions of the Higgs pair.