Search for Higgs Boson and Observation of Z Boson through Their Decay into a Charm Quark-Antiquark Pair in Boosted Topologies in Proton-Proton Collisions at sqrt[s]=13 TeV

A search for the standard model (SM) Higgs boson (H) produced with transverse momentum (p(T)) greater than 450 GeV and decaying to a charm quark-antiquark (c (c) over bar) pair is presented. The search is performed using proton-proton collision data collected at root s =13 TeV by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138 fb(-1). Boosted H -> c (c) over bar decay products are reconstructed as a single large-radius jet and identified using a deep neural network charm tagging technique. The method is validated by measuring the Z -> c (c) over bar decay process, which is observed in association with jets at high p(T) for the first time with a signal strength of 1.00(-0.14) (+0.17) (syst) +/- 0.08(theo) +/- 0.06 (stat), defined as the ratio of the observed process rate to the SM expectation. The observed (expected) upper limit on sigma(H) B (H ->(c) over bar) is set at 47 (39) times the SM prediction at 95% confidence level.