Search for the Higgs boson decays to a ρ⁰, ϕ, or K^⁎0 meson and a photon in proton-proton collisions at s=13TeV

Three rare decay processes of the Higgs boson to a ρ(770)⁰, ϕ(1020), or K^⁎(892)⁰ meson and a photon are searched for using s=13TeV proton-proton collision data collected by the CMS experiment at the LHC. Events are selected assuming the mesons decay into a pair of charged pions, a pair of charged kaons, or a charged kaon and pion, respectively. Depending on the Higgs boson production mode, different triggering and reconstruction techniques are adopted. The analyzed data sets correspond to integrated luminosities up to 138fb⁻¹, depending on the reconstructed final state. After combining various data sets and categories, no significant excess above the background expectations is observed. Upper limits at 95% confidence level on the Higgs boson branching fractions into ρ(770)⁰γ, ϕ(1020)γ, and K^⁎(892)⁰γ are determined to be 3.7×10⁻⁴, 3.0×10⁻⁴, and 3.0×10⁻⁴, respectively. In case of the ρ(770)⁰γ and ϕ(1020)γ channels, these are the most stringent experimental limits to date.