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We present a calculation of the NLO QCD corrections to Higgs boson pair production within the framework of a non-linearly realised Effective Field Theory in the Higgs sector, described by the electroweak chiral Lagrangian. We analyse how the NLO corrections affect distributions in the Higgs boson pair invariant mass and the transverse momentum of one of the Higgs bosons. We find that these corrections lead to significant and non-homogeneous K-factors in certain regions of the parameter space. We also provide an analytical parametrisation for the total cross-section and the m hh distribution as a function of the anomalous Higgs couplings that includes NLO corrections. Such a parametrisation can be useful for phenomenological studies.1 Sometimes the electroweak chiral Lagrangian with a light Higgs boson is also referred to as Higgs Effective Field Theory (HEFT) in the literature. The two EFTs are unrelated and should be carefully distinguished. Here we employ the term electroweak chiral Lagrangian for the non-linear EFT of physics beyond the SM, and reserve the expression HEFT for the heavy-top limit in Higgs interactions.Refs. [51-54]. The NNLO QCD corrections in the heavy-top limit have been computed in Refs. [52, 55-57], and they have been supplemented by an expansion in 1/m 2 t in Ref. [53] and by threshold resummation, at NLO+NNLL in Ref. [58] and at NNLO+NNLL in Ref. [59], leading to K-factors of about 1.2 relative to the Bornimproved HEFT result. The full NLO corrections, including the top quark mass dependence also in the virtual two-loop amplitudes, have been calculated in Ref. [60]. Phenomenological studies at 14 TeV and 100 TeV, including variations of the Higgs boson self-coupling, have been presented in Ref. [61]. The full NLO calculation was supplemented by NLL transverse momentum resummation in Ref. [62]. It also has been matched to parton shower Monte Carlo programs [63, 64], where the matched result of Ref. [63] is publicly available within the POWHEG-BOX-framework. Recent work also includes a combination of an analytic threshold expansion and a largem t expansion together with a Padé approximation framework [65], and analytic results based on a high energy expansion for the planar part of the two-loop amplitude [66]. Very recently, top quark mass effects have been incorporated in the NNLO HEFT calculation, including the full NLO result and combining one-loop double-real corrections with full top mass dependence with suitably reweighted real-virtual and double-virtual contributions evaluated in the large-m t approximation [67]. Within a non-linear EFT framework, higher order QCD corrections have been performed in the m t → ∞ limit. The NLO QCD corrections have been calculated in Ref. [68], recently also supplemented with the case of CP-violating Higgs sectors [69].The NNLO QCD corrections in the m t → ∞ limit including dimension 6 operators have been presented in Ref. [70]. These calculations found rather flat K-factors, which however could be an artefact of the m t → ∞ limit. One of the main goals...

We classify shapes of Higgs boson pair invariant mass distributions m hh , calculated at NLO with full top quark mass dependence, and visualise how distinct classes of shapes relate to the underlying coupling parameter space. Our study is based on a five-dimensional parameter space relevant for Higgs boson pair production in a non-linear Effective Field Theory framework. We use two approaches: an analysis based on predefined shape types and a classification into shape clusters based on unsupervised learning. We find that our method based on unsupervised learning is able to capture shape features very well and therefore allows a more detailed study of the impact of anomalous couplings on the m hh shape compared to more conventional approaches to a shape analysis.

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We discuss the interplay between NLO QCD corrections and anomalous couplings in Higgs boson pair production via gluon fusion, within the framework of a non-linearly realised Effective Field Theory, described by the electroweak chiral Lagrangian. We study how the NLO corrections with full top quark mass dependence affect the total cross sections as well as distributions in the Higgs boson pair invariant mass. For a large part of the parameter space, significant and non-homogeneous K-factors arise.

We discuss the interplay between NLO QCD corrections and anomalous couplings in Higgs boson pair production via gluon fusion, within the framework of a non-linearly realised Effective Field Theory, described by the electroweak chiral Lagrangian. We study how the NLO corrections with full top quark mass dependence affect the total cross sections as well as distributions in the Higgs boson pair invariant mass. For a large part of the parameter space, significant and non-homogeneous K-factors arise.

We study the impact of anomalous couplings in the Higgs sector on the shape of the Higgs boson pair invariant mass distribution at NLO. Our analysis is based on a five-dimensional coupling parameter space relevant for Higgs boson pair production in gluon fusion, in the framework of a non-linear Effective Field Theory. In particular, we present a clustering procedure into certain shape types based on unsupervised machine learning, with the aim to infer information about the underlying parameter space from a given shape type.

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