Search for rare decays of the Z and Higgs bosons to a J/ψ or ψ(2S) meson and a photon in proton-proton collisions at √s = 13 TeV

Abstract

A search is presented for rare decays of the [Figure presented] and Higgs bosons to a photon and a [Figure presented] or a [Figure presented] meson, with the charmonium state subsequentially decaying to a pair of muons. The data set corresponds to an integrated luminosity of 123fb−1 of proton-proton collisions at a center-of-mass energy of 13 TeV collected with the CMS detector at the LHC. No evidence for branching fractions of these rare decay channels larger than predicted in the standard model is observed. Upper limits at 95% confidence level are set: [Figure presented], [Figure presented], [Figure presented], and [Figure presented]. The ratio of the Higgs boson coupling modifiers [Figure presented] is constrained to be in the interval (−157,+199) at 95% confidence level. Assuming [Figure presented], this interval becomes (−166,+208). © 2025 CERN for the benefit of the CMS Collaboration