Simultaneous Probe of the Charm and Bottom Quark Yukawa Couplings Using t(t)over-barH Events

Abstract

A search for the standard model Higgs boson decaying to a charm quark-antiquark pair, H -> c (c) over bar, produced in association with a top quark-antiquark pair (t (t) over barH) is presented. The search is performed with data from proton-proton collisions at root 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 (t) over barH(H -> b (b) over bar) 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 sigma(t (t) over barH) B(H -> c (c) over bar) 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 -> c (c) over bar via associated production with a W or Z boson, the observed (expected) 95% confidence interval on the Higgs-charm Yukawa coupling modifier, kappa(c), is vertical bar kappa(c)vertical bar < 3.5 (2.7), the most stringent constraint to date.