Search for a massive scalar resonance decaying to a light scalar and a Higgs boson in the four b quarks final state with boosted topology

We search for new massive scalar particles X and Y through the resonant production process $X \rightarrow YH \rightarrow b\bar{b} b\bar{b}$, where H is the standard model Higgs boson. Data from CERN LHC proton-proton collisions are used, collected at a centre-of-mass energy of 13 TeV in 2016--2018 and corresponding to an integrated luminosity of 138 $\mathrm{fb}^{-1}$. The search is performed in mass ranges of 0.9--4 TeV for X and 60--600 GeV for Y, where both Y and H are reconstructed as Lorentz-boosted single large-area jets. The results are interpreted in the context of the next-to-minimal supersymmetric standard model and also in an extension of the standard model with two additional singlet scalar fields. The 95% confidence level upper limits for the production cross section very between 0.1 and 150 fb depending on the X and Y masses, and represent a significant improvement over results from previous searches.