Abstract: In 2012, the ATLAS and CMS collaborations announced the discovery of a new boson, which has so far remained compatible with that predicted by Higgs, Englert and Brout in the context of the Standard Model. However, the existence of any additional Higgs bosons would constitute unequivocal evidence for physics beyond the Standard Model (BSM). The ATLAS and CMS collaborations have been actively searching for such new particles, at masses both above and below that of the existing 125 GeV/c^2 Higgs boson; both cases are allowed by numerous BSM theories. In 2023 CMS followed by ATLAS released preliminary results of searches for a low-mass resonance in the diphoton decay mode exploiting the full set of proton-proton collision data collected during the LHC Run 2 (2016-2018). This seminar will describe the analysis techniques and discuss the results of the search from the two experiments.