Nonresonant pair production of highly energetic Higgs bosons decaying to bottom quarks

A search for nonresonant Higgs boson (H) pair production via gluon and vector boson (V) fusion is performed in the final state where each H decays to a bottom quark-antiquark pair, using $138\,\text{fb}^{-1}$ of proton-proton collision data collected by the CMS experiment at $\sqrt{s}=13\,\text{TeV}$. The analysis targets highly Lorentz-boosted H jets identified using a graph neural network classifier. The total HH production cross section is observed (expected) to be smaller than 9.9 (5.1) relative to the standard model (SM) prediction. The search also yields constraints on the coupling strengths relative to the SM of the H self-coupling, $\kappa_\lambda \in [-9.9, 16.9]$, the trilinear VVH coupling, $\kappa_\mathrm{V} \in [-1.17, -0.79] \cup [0.81, 1.18]$, and the quartic VVHH coupling, $\kappa_\mathrm{2V} \in [0.62, 1.41]$, at $95\%$ confidence level, excluding $\kappa_\mathrm{2V} = 0$ for the first time, when other H couplings are fixed to their SM values.