A search for an exotic decay of the Higgs boson to a Z boson and a light pseudoscalar particle (a), decaying to a
pair of leptons and a pair of photons, respectively, is presented. The search is based on proton-proton collision
data at a center-of-mass energy of √𝑠 = 13TeV, collected with the CMS detector at the LHC and corresponding
to an integrated luminosity of 138 fb−1. The analysis probes pseudoscalar masses 𝑚a between 1 and 30 GeV,
leading to two pairs of well-isolated leptons and photons. Upper limits at 95% confidence level are set on the
Higgs boson production cross section times its branching fraction to two leptons and two photons. The observed
(expected) limits are in the range of 1.1–17.8 (1.7–17.9) fb within the probed 𝑚a interval. An excess of data above
the expected standard model background with a local (global) significance of 2.6 (1.3) standard deviations is
observed for a mass hypothesis of 𝑚a = 3GeV. Limits on models involving axion-like particles, formulated as an
effective field theory, are also reported.