Date of this Version
PHYSICAL REVIEW LETTERS 131, 061801 (2023). DOI: 10.1103/PhysRevLett.131.061801
A search for the standard model Higgs boson decaying to a charm quark-antiquark pair, H → c, produced in association with a leptonically decaying V (W or Z) boson is presented. The search is performed with proton-proton collisions at √s = 13 TeV collected by the CMS experiment, corresponding to an integrated luminosity of 138 fb−1. Novel charm jet identification and analysis methods using machine learning techniques are employed. The analysis is validated by searching for Z → c in VZ events, leading to its first observation at a hadron collider with a significance of 5.7 standard deviations. The observed (expected) upper limit on σ(VH)B(H → c) is 0.94 (0.50+0.22−0.15 )pb at 95% confidence level (C.L.), corresponding to 14 (7.6+3.4−2.3 ) times the standard model prediction. For the Higgs-charm Yukawa coupling modifier, κc, the observed (expected) 95% C.L. interval is 1.1 < |κc| < 5.5 (|κc| < 3.4), the most stringent constraint to date.