Search for exotic Higgs boson decays H → AA with A → YY in events with a semi-merged topology in proton-proton collisions at √(s) = 13 TeV.

Abstract

A search for exotic Higgs boson decays H → 𝒜𝒜, with 𝒜 → γγ is presented, using events with a semi-merged topology. One of the hypothetical particles, 𝒜, is assumed to decay promptly into a semi-merged diphoton system reconstructed as a single photon-like object, while the other 𝒜 decays into two resolved photons. The search is performed using proton-proton collision data collected by the CMS experiment at TeV, corresponding to an integrated luminosity of 138 fb−1. The data agree with the standard model background expectation. Upper limits are set on the product of the Higgs boson production cross section and the branching fraction, σ(pp → H) ℬ(H → 𝒜𝒜 → 4γ), which range from 0.264 to 0.005 pb at 95% confidence level, for 𝒜 masses in the range 1 < m𝒜 < 15 GeV. These limits are the most stringent to date in the 1–5 GeV m𝒜 range.