Simultaneous probe of the charm and bottom quark Yukawa couplings using t t-bar H events

A search for the standard model Higgs boson decaying to a charm quark-antiquark pair, H → cc¯, produced in association with a top quark-antiquark pair (t¯tH) is presented. The search is performed with data from proton-proton collisions at radical(s) = 13 TeV, corresponding to an integrated luminosity of 138 fb−1. Advanced machine learning techniques are employed for jet flavor identification and event classification. The Higgs boson decay to a bottom quark-antiquark pair is measured simultaneously and the observed t¯tH(H → bb¯) event rate relative to the standard model expectation is 0.91 0.26 −0.22 . The observed (expected) upper limit on the product of production cross section and branching fraction σ(t¯tH)B(H → cc¯) is 0.11 (0.13) pb at 95% confidence level, corresponding to 7.8 (8.7) times the standard model prediction. When combined with the previous search for H → cc¯ via associated production with a W or Z boson, the observed (expected) 95% confidence interval on the Higgs-charm Yukawa coupling modifier, κc, is κc < 3.5 (2.7), the most stringent constraint to date.