SMEFT truncation effects in Higgs boson pair production at NLO QCD

We present results for Higgs boson pair production in gluon fusion at next-to-leading order in QCD, including effects of anomalous couplings within Standard Model Effective Field Theory (SMEFT). In particular, we investigate truncation effects of the SMEFT series, comparing different ways to treat powers of dimension-six operators and double operator insertions.