A search for a massive resonance X decaying to a pair of spin-0 bosons φ that themselves decay to pairs
of bottom quarks, is presented. The analysis is restricted to the mass ranges mφ from 25 to 100 GeV and
mX from 1 to 3 TeV. For these mass ranges, the decay products of each φ boson are expected to merge
into a single large-radius jet. Jet substructure and flavor identification techniques are used to identify
these jets. The search is based on CERN LHC proton-proton collision data at √s = 13 TeV, collected with
the CMS detector in 2016–2018, corresponding to an integrated luminosity of 138 fb−1. Model-specific
limits, where the two new particles arise from an extended Higgs sector, are set on the product of the
production cross section and branching fraction for X → φφ → (bb)(bb) as a function of the resonances’
masses, where both the X → φφ and φ → bb branching fractions are assumed to be 100%. These limits
are the first of their kind on this process, ranging between 30 and 1 fb at 95% confidence level for the
considered mass ranges.