Search for exotic Higgs boson decays H -> AA -> 4 gamma with events containing two merged diphotons in proton-proton collisions at sqrt(s) = 13 TeV

We present the first direct search for exotic Higgs boson decays H→AA, A→γγ in events with two photonlike objects. The hypothetical particle A is a low-mass spin-0 particle decaying promptly to a merged diphoton reconstructed as a single photonlike object. We analyze the data collected by the CMS experiment at √s=13  TeV corresponding to an integrated luminosity of 136  fb−1. No excess above the estimated background is found. We set upper limits on the branching fraction B(H→AA→4γ) of (0.9–3.3)×10−3 at 95% confidence level for masses of A in the range 0.1–1.2 GeV.