  We present the calculation of the full next-to-leading order (NLO) QCD
corrections to Higgs boson pair production via gluon fusion at the LHC,
including the exact top-mass dependence in the two-loop virtual and one-loop
real corrections. This is the first independent cross-check of the NLO QCD
corrections presented in the literature before. Our calculation relies on
numerical integrations of Feynman integrals, stabilised with
integration-by-parts and a Richardson extrapolation to the narrow width
approximation. We present results for the total cross section as well as for
the invariant Higgs-pair-mass distribution at the LHC, including for the first
time a study of the uncertainty due to the scheme and scale choice for the top
mass in the loops.
