Search for new resonances decaying to pairs of merged diphotons in proton-proton collisions at √s = 13 TeV

A search is presented for an extended Higgs sector with two new particles, X and φ, in the process X →φφ→(γγ)(γγ)$. Novel neural networks classify events with diphotons that are merged and determine the diphoton masses. The search uses LHC proton-proton collision data at $√s$ = 13 TeV collected with the CMS detector, corresponding to an integrated luminosity of 138 fb$⁻¹$. No evidence of such resonances is seen. Upper limits are set on the production cross section versus the resonance masses, representing the most sensitive search in this channel.