Search for new particles in an extended Higgs sector with four b quarks in the final state at s=13TeV

A search for a massive resonance X decaying to a pair of spin-0 bosons ? that themselves decay to pairs of bottom quarks, is presented. The analysis is restricted to the mass ranges m from 25 to 100 GeV and m from 1 to 3 TeV. For these mass ranges, the decay products of each ? 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=13TeV, collected with the CMS detector in 2016-2018, corresponding to an integrated luminosity of 138fb. 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->??->(bb?)(bb?) as a function of the resonances' masses, where both the X->?? and ?->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.