Search for anomalous couplings in ggH production in the di-photon channel with CMS Run 2 data

We study the sensitivity to anomalous couplings between the Higgs boson and gluons using data collected by the CMS detector during LHC Run 2, corresponding to an integrated luminosity of 138 fb⁻¹ at a center-of-mass energy of 13 TeV. In the Standard Model (SM), the coupling between the Higgs boson and gluons (Hgg) is mediated via a loop of top quarks. Anomalous Hgg couplings, absent from the SM, could arise from charge-parity (CP)-odd interactions between the Higgs boson and top quarks, and/or from effective couplings involving loops of heavy particles from beyond the Standard Model (BSM) interactions. We select data event candidates for Higgs bosons decaying in the diphoton channel, produced primarily through the gluon fusion mechanism with two additional jets, to investigate potential deviations from SM expectation. Multivariate techniques are employed to classify the data events into several categories sensitive to different anomalous Hgg couplings by analyzing the kinematic correlations between the Higgs-boson candidate and the associated hard-scatter jets. This approach effectively suppresses the combinatorial background from QCD diphoton production and reduces contamination from Higgs bosons produced via the vector boson fusion process, which is not sensitive to anomalous Hgg couplings. In addition, Matrix Element Likelihood Analysis (MELA) methods are utilized to discriminate between signal and background events, as well as to distinguish between different scalar and pseudoscalar Higgs states. We then perform statistical inference using a maximum likelihood fit across the different categories, leading to stringent constraints on the CP-odd anomalous coupling parameter.