Search for H→Zγ Decay at the Compact Muon Solenoid Experiment in llγ Final State

Since the discovery of the Higgs boson in 2012 its properties align with standard model predictions. The Higgs decay to a Z boson and a photon (H→Zγ) remains an unobserved decay whose coupling is sensitive to anomolous trilinear Higgs self-couplings and loop effects arising in composite Higgs models. To effectively target this decay we look for the final state of a dilepton pair (electrons or muons) decaying from the Z boson and a photon. Previous searches utilizing 137 inverse femtobarns of data collected by the CMS experiment yielded a best fit signal strength of 2.4 ± 0.9 and observed significance of 2.7σ (with 1.2σ expected). To enhance this search we plan to implement several several improvements including the addition of 2022 + 2023 data, refined trigger strategies, and dedicated categories targeting rare Higgs production modes. These enhancements improve the sensitivity to the H→Zγ decay and to potential physics beyond the standard model.